Math Problem Statement

Bill wants to save $700 to buy a TV. He saves $18 each week. The amount, A(w) (in dollars), that he still needs after w weeks is given by the function A(w) = 700 - 18w. (a) If Bill still needs $358, how many weeks has he been saving? (b) How much money does Bill still need after 7 weeks?

Solution

Let’s solve the questions in the uploaded image:

Problem Breakdown:

The equation provided is:

A(w)=70018wA(w) = 700 - 18w

where:

  • A(w)A(w) is the amount (in dollars) that Bill still needs to save.
  • ww is the number of weeks Bill has been saving.

Part (a):

If Bill still needs $358, how many weeks has he been saving?

Set A(w)=358A(w) = 358 and solve for ww: 358=70018w358 = 700 - 18w Rearrange: 18w=70035818w = 700 - 358 18w=34218w = 342 w=34218=19w = \frac{342}{18} = 19

So, Bill has been saving for 19 weeks.

Part (b):

How much money does Bill still need after 7 weeks?

Substitute w=7w = 7 into the equation: A(7)=70018(7)A(7) = 700 - 18(7) A(7)=700126A(7) = 700 - 126 A(7)=574A(7) = 574

So, Bill still needs $574 after 7 weeks.


Would you like additional explanation or further clarification? Here are some related questions to consider:

  1. How does the rate of savings ($18 per week) impact the time needed to reach $700?
  2. What would the equation look like if Bill increased his savings rate to $25 per week?
  3. How many total weeks would it take Bill to save exactly $700?
  4. If Bill started with $100 already saved, how would this change the equation?
  5. What is the maximum number of weeks Bill could save while still needing more than $0?

Tip: When working with linear equations in real-life problems, identify the rate (slope) and starting point (intercept) to simplify your calculations.

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Math Problem Analysis

Mathematical Concepts

Linear equations
Solving for variables
Substitution

Formulas

A(w) = 700 - 18w

Theorems

Properties of linear equations

Suitable Grade Level

Grades 6-8