Since you know that 4/9 and 1/5 are used, make them common denominators. So 4/9 would turn into 20/45 and 1/5 would be 9/45. It results in 29/45, but that is the amount spent, so you would subtract 45-29/45, resulting in 16/45. For B, you know that she spent 3/4 of the savings, so you know that 1/4 is not being spent. So use 1/4 multiplied by 16/45 from part A to get 4/45. For C, you know that 4/45 is $100, so I multiplied 45x100 to get 4500 and then divided by 4 to get 4500/4.
