Answer:
$2750.00 / 11 = $5250.00 / x (where x is the number of hours to earn $5250)
Solve in one of various ways -- let's cross multiply:
2750.00*x = 11*5250.00
x = 21 hours (divide both sides by 2750.00)
Checking (very important):
Is 2750.00 / 11 = 5250.00 / 21 Yes!