+ Bell Work The product of 20 and 10 is how much greater than the sum of 20 and 10?

+ Bell Work Answer: 200 – 30 = 170

+ Lesson 3: Addition and Subtraction Word Problems

+ Many word problems we solve with math have plots just like a novel or a story. Recognizing the plot helps us solve the problem.

+ Problems about combining* have an addition thought pattern. We can express a combining plot with a formula, which is an equation used to calculate a desired result. some + more = total

+ Example: in the first half of the game, Sophie scored 12 points. In the second half, she scored 15 points. How many points did she score in the whole game? In this story, two numbers are combined to make a total.

+ Problems about separating* have a subtraction thought pattern. starting amount – some went away = what is left

+ Example: Danny went to the store with a twenty dollar bill. He bout a loaf of bread and a half gallon of milk for a total of $4.83. How much should the clerk give him back?

+ The hike to the summit of Mt. Whitney began from the upper trailhead at 8365 feet. The elevation of Mt. Whitney’s summit is 14,496 feet. Which equation shows how to find the elevation gain from the trailhead to the summit? A) g = 14,496B) ,496 = g C) g – 14,496 = 8365D) 8365 – g = 14,496

+ One way of comparing* numbers is by subtraction. The difference shows us how much greater or how much less one number is compared to another number. greater – lesser = difference

+ We can use a similar formula for elapsed time. later – earlier = difference

+ Example: from 1990 to 2000, the population of Fort Worth increased from 447,619 to 534,694. What was the population increase?

+ Example: President John F. Kennedy was elected in 1960 at the age of 43. In what year was he born?

+ Practice: Which three words identify the three types of plots described in this lesson?

+ Practice: Write a story problem for this equation. $20.00 – a = $8.45

+ For the next couple problems, identify the plot, write an equation, and solve the problem.

+ Practice: From 1990 to 2000 the population of Garland increased from 180,635 to 215,768. How many more people lived in Garland in 2000 than in 1990?

+ Practice: Lexie went to the theater with $20.00 and left the theater with $ How much money did she spend at the theater? Explain why your answer is reasonable.

+ Practice: In the 3 8 th grade classrooms at Washington school, there are 29 students, 28 students, and 31 students. What is the total number of students in the three classrooms?

+ Practice: Write an equation that shows how to find how much change a customer should receive from $10.00 for a $6.29 purchase.

+ HW Lesson 3 #1-30