Question

A dollar bill weighs 1 gram , and a penny weighs 25 decigrams. how much do a dollar bill and a penny weigh together.

Answer 1

1 decigram (dg) = 0.1 g
so 25 dg = 2.5 gram

together they weigh 3.5 g
(or 35 dg)

Answer 2

The dollar bill and a penny together weigh 3.5 grams or 35 decigrams.

Explanation:

The important idea is that you can only add units if they are the same, grams + grams or decigrams + decigrams.

1. Suppose you want the answer in grams so you convert the weight of the penny to grams:

`25 decigrams*(0.1 grams)/(1 decigram) = 2.5 grams \\ 1 gram + 2.5 grams\\3.5 grams`

2. Suppose you want the answer in decigrams so you convert the weight of the dolar bill to decigrams:

`1 gram*(10decigrams)/(gram) = 10 decigrams \\ 10 decigrams + 25 decigrams\\35 decigrams`.