Answer:
$68,000
Explanation:
we have to determine the total economic costs of going to college = ($40,000 x 2) + ($30,000 x 2) = $140,000
since we want to recover our "college investment" in 5 years or less, then we must earn at least $140,000 / 5 = $28,000 more per year
the minimum salary that we should earn after graduating = $40,000 (our current salary) + $28,000 (to recover college costs) = $68,000