Answer:
80
Explanation:
To earn $51,000 he needs to earn $6,000 in commissions:
$51,000 - $45,000 base salary = $6,000
If he gets $75 for each computer he sells, he will need to sell ($6,000 / $75) computers.
That's 80 computers.
80 * $75 = $6,000
$45,000 + $6,000 $51,000