Pls tell me witch one it is

Asmall business produces and sells balls. the fixed costs are $20 and each ball costs $4.32 to produce. each ball sells for $8.32. write the equations for the total cost, c, and the revenue, r, then use the graphing method to determine how many balls must be sold to break even.

What is the missing value in the proportion 4/5 = x/30

Perform the indicated operation. y^2 + 3y - 10 / 3y + 15