You earn $100 plus 1/5 of your sales each week. What dollar amount of sales do you need this week to earn $600?

You'll need $2,500 in sales this week to end up with $600 in income for the week.

Step-by-step explanation:

Let s represent the dollar amount of the total sales for the week.

The commission earned on such sales is 1/5, or 0.20, of s:

Commission: 0.20s

Then the correct expression for your weekly income is:

$100 + 0.20s = $600.

Solving for s, subtract $100 from both sides. Then 0.20s = $500, and through division we get s = $2,500.

You'll need $2,500 in sales this week to end up with $600 in income for the week.