Question

An advertisement claims that a 5-pound box of detergent will wash 20 loads of laundry. A 5-pound box costs $3.50. A 15-pound box costs $10.00. About how much will you save per load if you buy the 15-pound box?

Answer 1

A 5-pound box is $3.50 so to prove 15-pound box has better value, you multiply by 3.

3.50 × 3 = $10.50

A 15-pound costs $10 so you save .50 for the load.

$10.50 - 10.00 = .50

Answer 2

5 pounds = 20 loads = $3.50

Convert to per-load:

1/4 pound = 1 load = 13.5 cents

15 pounds = 60 loads = $10

Convert to per-load:

1/4 pound = 1 loads = 16.7 cents

You would save 3.2 cents per load