so we solve for 1 week and set them equal to each other
first job pay=second job pay
400=175+15%ofsales
x=number of sales
400=175+0.15x
solve for x
subtract 175 from both sides
225=0.15x
divide both sides by 0.15
1500=x
she has to earn $1500 in sales per week to have as much as the other job