How i would solve it is
1. 72.6-35=37.6
2. 37.6/.05=752
and for April you can do the same process phone bill - 35 for usage then divide the answer by .05
4 and a half to fill
30 in total minus the ones already used 30 - 18 = 12
A forth of the pages she wants to save which is about 7.5 of the total
12 - 7.5
Means she only has 4.5 pages left to use before she starts using her extra vacation pages
