Please answer this question Geometry

Evaluate the dot product of (3,-1) and (1,5)

What is 20+(5 x 2/5 )+ 3 show your work

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.