What is the length of a phone call that would cost the same no matter which company is used?

Company A 35cents plus 3 cents per minute

Company B 45 cents plus 2 cents per minute

First, make an equations for each company

35+3x = Company A

45+2x = Company B

Then, equate the equations

35+3x = 45+2x

-2x - 2x

35 + x = 45

-35 - 35

x=10, So, 10 minutes will be the length of a phone call that would cost the same no matter which company is used.