Algebra and percents

Question

Amandas job offered two plans, plan A is a salary of $1,200 per month plus 6% commission on sales. Plan B is a salary of $1,600 per month and 4% commission on sales. For what amount of monthly sales is plan A better then plan B?

Answer 1

E = 1200 + .06S

E = 1600 +.04S

1200+.06S = 1600 +.04S

.02S = 400

S = 400/.02 = 400(50) = 20,000 with sales of $20,000 the earnings are the same for either job

Plan A is better for sales of more than $20,000