Ok. If you have 3 children, and it cost 10$ for each you would do 10x3 which equals 30. Then you have to baby sit for 3 hours you would do the same thing. 3.50x3 which equals 10.5. Then if you add 30 and 10.5, you will get your answer. So the answer is Becky will earn $40.50(Fourty dollars and 50 cents) or in other words $121.50