Let's write and equation for both cases.
In plan 1, it is 500 plus 3% comission. 3% is equivalent to multiply the amount it sale in the week, "x", by 0.03.
So, the equation for plan 1 is:
For plan 2, there is no fixed value, only comission of 5%, which is equivalent of multiplying the weekly sales, "x", by 0.05, so the equation is:
For both plans to result in the same salary, we have:
So, for both plans to result in the same salary, she have to sale 25,000 in a week.