Last year price per share: $17 1/4 = $17.25
Today's price per share: $17 3/8 = $17.325
This is equal to:
The number of shares I bought last year: 1000
The profit per share is:
$17.325 - $17.25 = $0.125
If I sell x shares to make $100 of profit, we have the equation:
0.125*x = 100
Solving for x, we divide both sides by 0.125:
0.125*x/0.125 = 100/0.125
But: 0.125 = 1/8
x = 100/(1/8)
x = 80
I need to sell 80 shares in order to make a profit of $100