Answer:
65.48weeks
Explanation:
Firstly, we know that his parent will pay half of the money
18,990/2=$9495
let us solve for Sam's weekly pay
weekly pay= 20*7.25
weekly pay=$145
Sam earns $145 per week
And the deficit for the car is $9495 (the parent paid half the price)
therefore the number of weeks Sam must work to pay the deficit is
=$9495/145
=65.48weeks