I need help with a word problem.

Question

Company A costs $30 with $0.25 per extra text message. While company B costs $45 with $0.10 per text message. At how many text messages are they the same costs?

Answer 1

A = 30 + 0.25*m

B = 45 + 0.10*m

What is m when A=B?

30 + 0.25*m = 45 + 0.10*m

30 + 0.25*m - 30 = 45 + 0.10*m - 30

0.25*m = 15 + 0.10*m

0.25*m - 0.10*m = 15 + 0.10*m - 0.10*m

0.15*m = 15

0.15*m/0.15 = 15/0.15

m = 100

When the number of messages m = 100, your bill is the same for either A or B.