Number of tests made =x
Verzon C(x) = 45 + 0.1x => 45+0.1*1200 =165
AT & T C(y) = 30 + 0.13x=> 30 + 0.13*1200=186
For 1200 texts C(x) is less than C(y)
If the costs are to be the same then
45 + 0.1x = 30 + 0.13x
15=0.03x
15/0.03= x
500=x
500 texts
7.5m questions
10.0m answers