How do you write an expression for 6 less than x

What term makes it inconsistent y=2x - 4 ?

How do you solve a question like this?

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.