How do you re-write 7-15 into a addition expression

I'll give brainliest if you answer right : )

For the equations below which statement is true ? -2x=14 6x=-42

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.