Add or Subtract Fractions With Different Denominators Advanced Online Quiz

Answer : A

Explanation

Step 1:

$\frac{2}{5}$ + $\frac{3}{8}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 5 × 8 = 40.

Step 2:

Rewriting as equivalent fractions

$\frac{16}{40}$ + $\frac{15}{40}$ = $\frac{(16+15)}{40}$ = $\frac{31}{40}$

Step 3:

So, $\frac{2}{5}$ + $\frac{3}{8}$ = $\frac{31}{40}$

Answer : D

Explanation

Step 1:

$\frac{5}{8}$ − $\frac{7}{12}$

Here the fractions have unlike denominators. So we find LCD. LCD is 24.

Step 2:

Rewriting as equivalent fractions

$\frac{15}{24}$ − $\frac{14}{24}$ = $\frac{(15-14)}{24}$ = $\frac{1}{24}$

Step 3:

So, $\frac{5}{8}$ − $\frac{7}{12}$ = $\frac{1}{24}$

Answer : C

Explanation

Step 1:

$\frac{2}{7}$ + $\frac{3}{8}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 7 × 8 = 56.

Step 2:

Rewriting as equivalent fractions

$\frac{16}{56}$ + $\frac{21}{56}$ = $\frac{(16+21)}{56}$ = $\frac{37}{56}$

Step 3:

So, $\frac{2}{7}$ + $\frac{3}{8}$ = $\frac{37}{56}$

Answer : B

Explanation

Step 1:

$\frac{6}{5}$ − $\frac{5}{7}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 5 × 7 = 35.

Step 2:

Rewriting as equivalent fractions

$\frac{42}{35}$ − $\frac{25}{35}$ = $\frac{(42-25)}{35}$ = $\frac{17}{35}$

Step 3:

So, $\frac{6}{5}$ − $\frac{5}{7}$ = $\frac{17}{35}$

Answer : A

Explanation

Step 1:

$\frac{2}{7}$ + $\frac{5}{9}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 7 × 9 = 63.

Step 2:

Rewriting as equivalent fractions

$\frac{18}{63}$ + $\frac{35}{63}$ = $\frac{(18+35)}{63}$ = $\frac{53}{63}$

Step 3:

So, $\frac{2}{7}$ + $\frac{5}{9}$ = $\frac{53}{63}$

Answer : B

Explanation

Step 1:

$\frac{5}{7}$ - $\frac{7}{11}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 7 × 11 = 77.

Step 2:

Rewriting as equivalent fractions

$\frac{55}{77}$ − $\frac{49}{77}$ = $\frac{(55-49)}{77}$ = $\frac{6}{77}$

Step 3:

So, $\frac{5}{7}$ - $\frac{7}{11}$ = $\frac{6}{77}$

Answer : C

Explanation

Step 1:

$\frac{2}{5}$ + $\frac{4}{9}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 5 × 9 = 45.

Step 2:

Rewriting as equivalent fractions

$\frac{18}{45}$ + $\frac{20}{45}$ = $\frac{(18+20)}{45}$ = $\frac{38}{45}$

Step 3:

So, $\frac{2}{5}$ + $\frac{4}{9}$ = $\frac{38}{45}$

Answer : D

Explanation

Step 1:

$\frac{7}{8}$ − $\frac{9}{12}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 24.

Step 2:

Rewriting as equivalent fractions

$\frac{21}{24}$ − $\frac{18}{24}$ = $\frac{(21-18)}{24}$ = $\frac{3}{24}$ = $\frac{1}{8}$

Step 3:

So, $\frac{7}{8}$ − $\frac{9}{12}$ = $\frac{1}{8}$

Answer : A

Explanation

Step 1:

$\frac{3}{5}$ + $\frac{2}{8}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 5 × 8 = 40

Step 2:

Rewriting as equivalent fractions

$\frac{24}{40}$ + $\frac{10}{40}$ = $\frac{(24+10)}{40}$ = $\frac{34}{40}$ = $\frac{17}{20}$

Step 3:

So, $\frac{3}{5}$ + $\frac{2}{8}$ = $\frac{17}{20}$

Answer : B

Explanation

Step 1:

$\frac{7}{8}$ - $\frac{8}{11}$

Here the fractions have unlike denominators. So we find LCD.

LCD is 8 × 11 = 88

Step 2:

Rewriting as equivalent fractions

$\frac{77}{88}$ − $\frac{64}{88}$ = $\frac{(77-64)}{88}$ = $\frac{13}{88}$

Step 3:

So, $\frac{7}{8}$ - $\frac{8}{11}$ = $\frac{13}{88}$