Question

A pail with 40 washers in it weighs 500 grams. The same pail with 20 washers in it weighs 420 grams. How much does the pail weigh?

Answer 1

Pail weighs `340` grams.

Explanation:

A pail with `20` washers weighs `420` grams.

when `20` more washers are added it is pail with `40` washers and weighs `500` grams

Hence `20` washers weigh `500-420=80` grams

and each washer weighs `80/20=4` grams

and pail with `20` washers weighs `420` grams and `20` washers weigh `80` grams

Hence, pail weighs `420-80=340` grams.