Answer:
$13.50
Explanation:
To find Lucas's profit, subtract the cost from his total gain.
Lucas bought 6 packs for $4 each.
6 * $4 = $24
His cost is $24.
In each of the 6 packs, there were 25 pens.
6 * 25 = 150 total pens
Lucas sold each pen for $0.25
150 * $0.25 = $37.50
$37.50 - $24 = $13.50