Fred spent half of his allowance going to the movies. He washed the family car and earned 9 dollars. What is his weekly allowance if he ended with 11 dollars?

Weekly allowance $4

Step-by-step explanation:

Fred ended with $11. So, subtract $9 from washing the car.

$11 - $9 = $2

$2 Is the amount of weekly allowance Fred hasn't spent yet. However, at the beginning of the week, Fred used half his allowance. This means $2 was what was left. So,

$2 * 2 = $4

meaning Fred had $4 in allowance at the beginning of the week.