1. by Monica Yuskaitis, M.A.Ed
6th Grade
Algebra 3
Solving Equations with
Addition & Subtraction
n + 2 = 7
by Monica Yuskaitis, M.A.Ed
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2. Essential Question
How can I simplify and solve addition and subtraction equations?
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Vocabulary 3
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Vocabulary
Equation – A mathematical sentence stating that 2 expressions are equal.
12 – 3 = 9
13 = 9 + 4
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Vocabulary
Equation – A mathematical sentence with an equals sign.
16 – 5 = 11
17 =
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Vocabulary
Equals Sign (=) means that the amount is the same on both sides.
4 + 2 = 6
3 = 5 – 2
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Understanding
Equations 7
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An Equation is like a balance scale. Everything must be equal on both sides. =
5 + 5 10
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9. When the amounts are equal on both sides it is a true equation.= 12
6 + 6
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10. When the amounts are unequal on both sides it is a false equation.=
2 + 2 8
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When an amount is unknown on one side of the equation it is an open equation. =
n + 2 7
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When you find a number for n you change the open equation to a true equation. You solve the equation. = 7
n + 2 5
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13. Are these equations true, false or open?
= 5
= 17
n + 4 = 7
12 – 3 = 8
3 + v = 13
15 – 6 = 9
true
open
false
open
true
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Solving Addition
Equations 14
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Vocabulary
Inverse operation – the opposite operation used to undo the first.
4 + 3 = 7 7 – 4 = 3
6 x 6 = / 6 = 6
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16. How to solve an addition equation
Use the inverse operation for addition which is subtraction
m + 8 = = 4
m = = 12
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Think of the balance scale. If you can isolate n on 1 side you can solve the equation. =
n + 2 7
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Isolate n by using the inverse operation of addition, subtraction, and subtract 2 from both sides. =
n + 2 7 -2 -2
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19. If you have +2 and –2 what is your answer? Right 0.=
n + 2 7 -2 -2 5
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20. Now look at your balance scale. n = 5
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21. Substitute 5 in to see if it works.= 7 5
n+2
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22. Solve these equations using the inverse operation3
n + 4 = 7
5 + n = 1 4
n + 7 = 17
8 + n = 13
n + 7 = 15
9 + n = 17 9 10 5 8 8
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Solving Subtraction
Equations 23
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24. How to solve a subtraction equation
Use the inverse operation for subtraction which is addition
m - 3 = 5
5 + 3 = m
m = 8
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Think of the balance scale. If you can isolate n on 1 side you can solve the equation. = 9
n - 4
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26. Copyright 2013 © by Monica Yuskaitis
Isolate n by using the inverse operation of subtraction, addition, and add 4 to both sides. = 9
n - 4 +4 +4
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27. If you have +4 and –4 what is your answer? Right 0.= 9
n - 4 +4 +4 13
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28. Now look at your balance scale. n = 13
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29. Substitute 13 in to see if it works.= 9 13
n-4
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30. Solve these equations using the inverse operations16
n - 7 = 9
n – 8 = 4
n - 6 = 19
n – 8 = 13
n - 10 = 16
n – 21 = 43 12 25 21 26 64
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Find the value of n
43 + n = 59
n – 20 = 0
19 + n = 37
n - 32 = 17
87 + n = 105
n – 0 = 5
n = 16
n = 20
n = 18
n = 49
n = 18
n = 5
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Problem
Solving 32
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Raking Leaves
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34. Analysis Representation Resolution Problem Solving Steps
What information do you need?
What is the problem asking you to find out?
Is the answer going to be larger or smaller?
Representation
What strategies will you use?
What operations will you use?
How many steps are there and in what order must you do them?
How will you solve the problem?
Did you check your answer?
Does your answer make sense?
Resolution
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35. Copyright 2013 © by Monica Yuskaitis
Marcus had $43. He worked all day Saturday raking leaves and then had a total of $89. How much did he earn raking leaves?
43 + n = 89
n = $46 35
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36. Your parents would be so proud!
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