Adding Unlike Fractions

ADDING AND SUBTRACTING UNLIKE FRACTIONS

Multiple Choice

What is the sum of  $$\frac{25}{50}+\frac{30}{50}$$ ?

• $$1\frac{1}{10}$$  

• $$\frac{55}{100}$$  

• $$\frac{11}{20}$$  

Multiple Choice

Find the difference. 
$$\frac{13}{121}-\frac{11}{121}$$  

• $$\frac{2}{121}$$  

• $$\frac{5}{121}$$  

• $$\frac{1}{121}$$  

Multiple Choice

What are unlike fractions?

• Fractions that have the same numerator.

• Fractions that have the same denominators.

• Fractions that have the same numerator and denominator.

• Fractions that have different denominators.

HOW DO WE ADD OR SUBTRACT UNLIKE FRACTION?

2 Ways to ADD OR SUBTRACT UNLIKE FRACTIONS

METHOD 1: MULTIPLY THE DENOMINATORS AND NUMERATORS.

 $\frac{7}{9}-\frac{2}{3}$  

We multiply  each fraction by the opposite denominators.

 $\frac{3}{3}\times\frac{7}{9}-\frac{2}{3}\times\frac{9}{9}$  

ALWAYS SIMPLIFY YOUR ANSWER:

 $\frac{3}{3}\times\frac{7}{9}-\frac{2}{3}\times\frac{9}{9}$  = $\frac{21}{27}-\frac{18}{27}=\frac{3}{27}=\frac{1}{9}$  

Multiple Choice

You try:

• $$\frac{5}{13}$$

• $$\frac{5}{16}$$

• $$\frac{1}{4}$$

METHOD 2: FIND THE LEAST COMMON DENOMINATOR.

 $\frac{2}{3}+\frac{1}{4}$  

Multiple Choice

What is the least common denominator of 12 and 36?

• 6

• 12

• 36

• 4

Multiple Choice

What is the LCD of 12 and 15?

• 15

• 12

• 4

• 60

Poll

WHICH METHOD IS EASIER?

• METHOD 1 (Multiplication of denominators)

• METHOD 2 (Finding the LCD)