1."Did you get my envelopes?" Andy asked his son. "I need one right away." Peter nodded. "Sure, Dad. Seventeen in all, and two sizes, as you said," he replied. "The big ones were one pence each more than the others, and they came to 80 pence for the lot." How many of each size did he buy?

12 at 5p each, 5 at 4p each

18 at 3p each, 4 at 2p each

12 at 7p each, 6 at 6p each