Sum means add
sum of the 3 is
n+n+1+n+2
it add to 57
n+n+1+n+2=57
3n+3=57
minus 3 both sides
3n=54
divide both sides by 3
n=15
n+1=16
n+2=17
the integers are 15,16, and 17
1: 5,800
2: 112.5 (total weight, divide by 2, subtract 17 lb)
5: .8 (4 divided by 5)
6:

7: 1,728
9: 9 inches
10: 1.2
Sorry I couldn't give you all of them :(
When it says per month, it means to multiply. In this case, the expression would be;
25x+50
So however many months Fatima has spent at the gym, you would multiply that times 25 and add the initiation fee. Hope this helps.