Gym Membership Cost Calculation

A local gym offers a membership plan that has a one-time registration fee of $50 and a monthly fee of $30. The gym wants to determine the cost $C$, in dollars, of membership for $m$ months. The relationship between the total cost and the number of months can be represented by a linear function.

Calculate the cost of membership after 6 months. Write your answer as an integer in the grid below.