What is the volume of the sphere with a radiuse of 9 inches

How many $20 bills do you need to have to make $280

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.

With finding limits of multi variable !