100% - 7% - 30% = 63% of people are on the sand
Since x dollars is the total monthly sales Paul makes when his sales exceed 20,000 dollars, then the function f(x) should add x dollars and $20,000. The answer is B. x+20,000.
Assuming that x dollars is still the sales after gaining $20,000, then 15 percent of x is modeled by B. 0.15x.