How do you add and subtract fractions with different denominators like for ex
4 2/7 + 3 1/2 or 7/8 - 1/4
2007-09-30 08:32:09 · 2 answers · asked by Anonymous in Education & Reference ➔ Homework Help
If the fractions are mixed numbers as in your first example then you need to convert them into an improper fraction. Then you need to convert the denominators so that they are similar.
ex.
1.)
4 2/7 + 3 1/2 =
30/7 + 7/2 *multiply 30/7 by 2/2(=1) and multiply 7/2 by 7/7(=1)
60/14 + 49/14 =
109/14 *convert back to mixed number
Answer: 7 11/14
2.)
7/8 - 1/4 *multiply 1/4 by 2/2 (=1)
7/8 - 2/8 =
Answer: 5/8
2007-09-30 08:47:32 · answer #1 · answered by Stephanie S 1 · 0⤊ 1⤋
1. Change the fraction of 4 2/7 to 30/7 and 3 1/2 to 7/2
30/7 +7/2= LCD is 14
30/7=60/14
7/2= 49/14
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109/14=7 11/14
7/8-1/4
LCD is 8
7/8-2/8=5/8
2007-09-30 16:31:12 · answer #2 · answered by Dave aka Spider Monkey 7 · 0⤊ 1⤋