Two customers went to the post office to buy postcards and large envelopes. Each postcard costs the same amount and each large envelope costs the same amount. What was the cost in dollars of each large envelope? The first customer paid $24 for 16 postcards and 8 large envelopes.
The second customer paid $36 for 12 postcards and 18 large envelopes.

$0.75
$1.50
$1.15
$0.25