Answer: 2,160 pieces of mail
Explanation:
If every 10 seconds he sorts 8 pieces, then you have to first figure out how many pieces he sorts in 1 minute.
1 minute = 60 seconds
Divide 10 into 60 which = 6 times that he sorts mail in a minute.
Multiply 6 times 8 pieces = 48 pieces.
1 minute = 48 pieces
48 pieces times 45 minutes = 2,160 pieces of mail.
Brandon sorts 2,160 pieces of mail in 45 minutes.