Answer: Ollie earned $9 per hour.
Explanation:
Let x represent the amount that Ollie earned per hour.
Stan and Ollie each earned the same amount last week Stan work 20 hours and earned $13.50 per hour. This means that the total amount that Stan earned would be
20 × 13.5 = $270
Ollie worked 30 hours. This means that the total amount that Ollie earned would be
30 × x = $30x
Since they earned the same amount, then
30x = 270
x = 270/30 = $9 per hour