Carol gets a fixed $20 allowance each week. She can also earn $1.5 more dollars each week if she does extra chores. At the end of 10 weeks, she has 425 dollars. How many extra chores did she average each week?
She earned $42.5 on average per week because 425 / 10 = <T>divide(425, 10)=42.5
She earned $22.5 each week from extra chores because 42.5 - 20 = <T>subtract(42.5, 20)=22.5
She did 15 extra chores a week because 22.5 / 1.5 = <T>divide(22.5, 1.5)=15.0
