Answer:
8.9 cm
Step-by-step explanation:
We have
$53.30
61.43-21.75=39.68 is the cell phone bill in July.
39.68+13.62= 53.30 is the phone bill in June.
I think it is 710
$18.30
100 - 26.80 = 73.20
73.20 / 4 = 18.30