Help with math please. Long question.

Question

Customers of a phone company can choose between two service plans for long distance calls. The first plan has a $23 monthly fee and charges an additional $0.11 for each minute of calls. The second plan has no monthly fee but charges $0.15 for each minute of calls. For how many minutes of calls will the costs of the two plans be equal?

Answer 1

C₁(x) = 23 + 0.11x; C₂(x) = 0.15x;

C₁(x) = C₂(x); 23 + 0.11x = 0.15x; 0.04x = 23; x = 575 minutes