Given:
$3,600 initial investment in stock
$30 profit for each share upon selling of the stock
$2,400 total profit
2,400 = 30x
2,400/30 = x
80 = x
He purchased 80 shares.
3,600/80 = 45 purchase price per share.
45 + 30 = 75 selling price per share
total profit = sales - cost
2,400 = (75*80) - 3,600
2,400 = 6,000 - 3,600
2,400 = 2,400
