Final answer:
Working backwards from the $18 Jason had after spending half his allowance and earning $7, we add the $7 to $18, getting $25, which is half his allowance. Multiplying $25 by 2 calculates his full weekly allowance, which is $50.
Step-by-step explanation:
To solve for Jason's weekly allowance, we have to work backwards from the information provided. Jason ended with $18 after spending half of his allowance and earning an additional 7 dollars by washing the car.
First, let's add back the $7 he earned to the $18 he ended up with, which gives us $25 ($18 + $7 = $25). This $25 represents half of his weekly allowance because he spent the other half on movies. To find his full allowance, we then multiply $25 by 2.
$25 Ă— 2 = $50
So, Jason's weekly allowance is $50.