let x = orginal price of the shorts
$21 = x(100%-20%) * 1.05
$21 = x(80%) * 1.05
$21 = 0.8x * 1.05
Subtract 1.05 from both sides
$19.95 = 0.8x
Divide 0.8 from both sides
$24.9375 = x
So the orginal price of the shorts are about $24.94
