9(p-4) = -18 Please help guys!

Can someone me with this problem i don't understand i need

Write an equation for the function that includes the points (1,4/5) and (2,2/3)

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.