Question 158932
This is an example of a linear equation y= mx + b

He started of with a specific amount of $40- this is b the constant value.This $40 is going to be used for the purchase. We know the value of y which is the total cost of the playstation 2= $129. We know that he plans to make the purchase in 4 months which is equivalent to 16 weeks.Each month contains 4 weeks.  In this equation it represents the slope of the line-m. X= to the amount of money that he needs to save each week. Therefore, we can solve this problem:

$129-40=16x  $5.57 is approximate the amount of money he needs to save per week.