Marcus's hourly income = $8.50
Amount that has already been saved by Marcus = $50
If Marcus wants to earn at least $475 for a new computer:
Let the amount of hours he will work to earn $475 = t
Since he earns $8.50 hourly and he already saved $475, the inequality will be of the form:
50 + 8.50t ≥ 475
8.50t ≥ 475 - 50
8.50t ≥ 425
t ≥ 425 / 8.50
t ≥ 50
Marcus must work for at least 50 hours