### Home > CC1 > Chapter 3 > Lesson 3.1.6 > Problem3-85

3-85.

David wants to find $\frac { 3 } { 10 } + \frac { 21 } { 100 }$ and is wondering if using decimals can help him make sense of adding fractions. Homework Help ✎

1. How could $\frac { 3 } { 10 } + \frac { 21 } { 100 }$ be written using decimals? What is the sum as a decimal?

$\frac{1}{10}=0.1,\ \frac{1}{100}=0.01$

0.3 + 0.21 = 0.51

2. How could your answer from part (a) be written as a fraction?

Use a denominator of 100.

3. Rewrite $\frac { 3 } { 10 }$ as a fraction that could be added easily to $\frac { 21 } { 100 }$.

Write as a fraction with a denominator of 100.

$\frac{30}{100}$