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