Steps
What is the first step when adding or subtracting fractions with unlike denominators?
Find the common denominator (LCM)
18
2 x 3 x 3
1 1
____ - ___ =
3 4
1
___
12
1 3
2 ____ + 1 ___ =
3 4
1
4 ____
12
From a board 8 feet in length, Emmet cut 2 1/3-foot bookshelves. How much of the board remained?
3 1/3 feet
What is the second step when adding or subtracting fractions with unlike denominators?
Write equivalent fractions with your new denominator
24
2 x 2 x 2 x 3
2 1
____ - ___ =
3 5
7
____
15
1 1
4 ____ + 2 ___ =
8 3
11
6 ____
24
Mia bought a bag of grapefruit, 1 5/8 pounds of strawberries, and 2 3/16 pounds of mangoes. The total weight of her purchases was 7 1/2 pounds. How much did the bag of grapefruit weigh?
3 11/16 pounds
What is the third step when adding or subtracting fractions with unlike denomiantors?
Add or subtract the numerator (keep the denominator)
32
2 x 2 x 2 x 2 x 2
1 1
____ - ___ =
2 5
3
____
10
6 3
6 ____ - 2 ___ =
7 4
3
4 ____
28
Audrey bought a 50-foot roll of packing tape. She used two 8 5/6-foot lengths. How much tape is left on the roll?
32 1/3 feet
What is the fourth step when adding or subtracting fraction with unlike denomiantors?
Simplify the fraction if needed
67
none, 67 is a prime number
4 2
____ - ___ =
5 3
2
____
15
1 4
3 ____ - ___ =
5 6
8
2 ____
15
Anthony rides his bike 7/8 mile to school. Zaylee rides her bike 1/2 mile to school. Who rides further?
Anthony rides 3/8 mile further.
What is the fifth step when adding or subtracting fractions with unlike denominators?
If improper, change to a mixed number fraction
134
2 x 67
5 1
____ - ___ =
7 3
8
____
21
1 ( 2 9 )
2 ____ + ( 1 ___ + 2 ______)=
10 ( 7 10 )
2
8 ____
7
Matthew spent 1/5 of his allowance on a movie ticket and 1/4 of his allowance on a snack. How much of his allowance did Matthew spend?
Matthew spent 9/20 of his allowance.