Hello, I need help on these math questions:

Thank you very much!

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

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.