### Home > CC1 > Chapter 3 > Lesson 3.2.2 > Problem3-107

3-107.

Find common denominators and calculate each of the following sums. Homework Help ✎

1. $\frac { 3 } { 8 } + \frac { 1 } { 4 }$

Remember, the denominator is the bottom number of a fraction. Here the denominators are 8 and 4. Can you change the fractions so that both denominators are 8?

$\frac{5}{8}$

2. $\frac { 2 } { 5 } + \frac { 1 } { 3 }$

Here, you might like to find the least common multiple of 5 and 3. This number should eventually be your common denominator.

3 and 5 have a least common multiple of 15.

$\text{Use multiplication to convert }\frac{2}{5}\text{ and } \frac{1}{3}$

to fractions with a denominator of 15.

$\text{If } \frac{2}{5}+\frac{1}{3}=\frac{6}{15}+\frac{5}{15},\text{ can you find the final sum?}$