1. PRE-ALGEBRA

2. Lesson 7-4 Warm-Up

3. PRE-ALGEBRA Reasoning Stategies: Write an Equation (7-4) To write a word problem into an equation: 1. understand what the problem is asking, 2. make a plan, 3. carry out the plan, and 4. check your answer to make sure it’s reasonable Example: To rent a moving van costs $29.95 / day plus $0.12 / mile. If your total bill came to $70.46, how many miles did you drive? Step 1: Understand what the problem is asking and what information is given What I need to find out: How many miles were driven? Days rented: 2 Cost per day (without milage): $29.95 Cost per mile: $0.12 Total cost:$70.46 Step 2: Make a plan (write an equation) Words: (two days · cost per day) + (cost per mile · number of miles) = $70.46 Let m = number of miles Equation: ( 2 · 29.95 ) + ( 0.12 · m ) = 70.46 How do you write an equation from a word problem?

4. PRE-ALGEBRA Reasoning Stategies: Write an Equation (7-4) Step 3: Carry out plan (solve your equation) (2 · 29.95) + (0.12 · m ) = 70.46 59.9 + 0.12m = 70.46Simplify 59.9 – 59.9 + 0.12m = 70.46 – 59.9Subtract 59.9 from each side to get rid of it on the m side 0.12m = 10.56Simplify 0.12m = 10.56Divide each side by 0.12 0.12 0.12to get rid of it on the m side 1m = 88Simplify Step 4: Check: (2 · 29.95) + 0.12 (88) = 59.9 + 10.56 = 70.46 1 1

5. PRE-ALGEBRA A moving van rents for $29.95 a day plus $.12 a mile. Mr. Reynolds’s bill was $137.80 and he drove the van 150 mi. For how many days did he have the van? Words number of days $29.95/d + $.12/mi 150 mi$137.80 = Let d = number of days Mr. Reynolds had the van. Equation 137.80d 29.95 + 0.12 150 = Reasoning Strategy: Write an Equation LESSON 7-4 Additional Examples

6. PRE-ALGEBRA (continued) Mr. Reynolds had the van for 4 days. d 29.95 + 0.12 150 = 137.80 29.95d + 18 = 137.80Multiply 0.12 and 150. 29.95d + 18 – 18 = 137.80 – 18Subtract 18 from each side. 29.95d = 119.80Simplify. d = 4Simplify. Divide each side by 29.95. = 29.95d 29.95 119.80 29.95 Reasoning Strategy: Write an Equation LESSON 7-4 Additional Examples

7. PRE-ALGEBRA Write an equation. Then solve. 1. You buy 2 pounds of sliced roast beef for $3 per pound and some smoked turkey for $5 per pound. You spend $13.50. How much turkey did you buy? 2. A phone call costs $.35 for the first minute and $.15 for each additional minute. The phone call cost $2.30. How many minutes did the call last? 14 minutes 1.5 lb LESSON 7-4 Lesson Quiz Reasoning Strategy: Write an Equation