$19.99 x 4 = $79.96
$22.50 x 6 = $135
$19.99 x 6 = $119.94
$22.50 x 4 = $90
The best answer to this choice is 4 dvds for $19.99. why?, because if it was 6 or 4 dvds for $19.99 the price would be more inexpensive then the price for $22.50, because if it was 22.50 x 4 or 6 dvds the price would be more expensive.