Adding and Subtracting Fractions with Unlike Denominators

What must you have to add and subtract fractions?

• Common numerators

• Different numerators

• Different denominators

• Common denominators

When you add or subtract fractions with unlike denominators you..

• Add both the numerators and denominators

• Change the denominator by picking a random number then divide

• Find the least common multiple of both denominators

• none of these are true

• 5/6
• 1
• 1  1/6
• 8/6

• - 3/56
• 18/56
• - 4/15
• 29/56

Solve and simplify if needed:

1/3 - 1/5 =

Mathematical Equivalence

OFF

What is the sum of these fractions in lowest terms?

• 4/5

• 3/20

• 17/20

• 4/20

Is this a correct answer?

• Yes, the student correctly added.

• No, you cannot add unlike denominators

• No, 5 + 7 is not 12

• No, 2 + 3 is not 5

What is the least common denominator for this problem? 3/16 + 2/4 =

• 24

• 8

• 16

• 32

What is the least common denominator of 1/4 and 1/3?

• 4

• 3

• 12

• 8

What is the least common denominator of 1/4 and 2/5?

• 5

• 25

• 10

• 20