Need Step By Step Guide

Question

One employee is paid base salary of 2000 a month plus 8% commission on all sales over 7000 during the month. How much does one need to sell in a month to earn a total of 4000?

The book says the answer is 34000 but I can’t figure it out

Answer 1

y = mx + b

y = (.08)(x - 7000) + 2000

4000 = (.08)(x - 7000) + 2000

4000 = .08x - 560 + 2000

2000 = .08x - 560

2560 = .08x

x = 32000

Earn 2000 and also earn 8% of 25000, which is 2000.