Alex has $20, and ellen has $12. alex is saving $3 per day, and ellen is saveing $5 per day. after how many days will alex and ellen have the same amount of money?

X - the number of days;
20 + 3 x = 12 + 5 x
20 - 12 = 5 x - 3 x
8 = 2 x
x = 8 : 2
x = 4
After 4 days they will have the same amount of money.
Alex :  20 + 4*3 = 20 + 12 = $32
Ellen:  12 + 4 * 5 = 12 + 20 = $32

The amount used= 13.04- 1.9 = 11.14