Edward deposited $9,000 into a savings account 3 years ago. The simple interest rate is 5%. How much money did Edward earn in interest? Please help im behind in math

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.