Hi I could use some help on these questions.

Suppose a Kindel manufacturer has the total cost function

C(x) = 145X + 26500

and the total revenue function

R(x) = 255X

where x is the number of Kindels.

-Find C(15)

-What is the equation of the profit function for this commodity?

-What is the profit on 50 items?

-How many items must be sold in a month to break even?(Or when is the profit zero?)