Question

A new pencil weighs 25 grams. After the pencil has been used for a while, it weighs 2 decagrams. How many grams of the pencil have been used up

Answer 1

5 grams of the pencil have been used up.

Answer 2

5 grams have been used up.

2 decagrams = 20 grams

You originated with 25.

25 - 5 = 20

Therefore the answer is 5 grams.