Bought 300 shares at $32:
300 x 32 = $9,600
Sold 300 shares at $20:
300 x 20 = $6,000
A) The loss was 9,600 - 6,000 = $3,600
B) Divide the loss by the purchase price:
3600 / 9600 = 0.375 = 37.5% loss.