Create an equation to match my polynomial

Just tell me how to set up the equation.

If y varies directly as x2 and y=6 when x=6, find the constant of variation.

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.