Subtract 9/7 from 21/15, Solve 1 6/15

Subtract 9/7 from 21/15

1^st number: 1 6/15, 2^nd number: 1 2/7

21/15 - 9/7 is 4/35.

Find the least common denominator or LCM of the two denominators:
LCM of 15 and 7 is 105

Next, find the equivalent fraction of both fractional numbers with denominator 105
For the 1st fraction, since 15 × 7 = 105,
21/15 = 21 × 7/15 × 7 = 147/105
Likewise, for the 2nd fraction, since 7 × 15 = 105,
9/7 = 9 × 15/7 × 15 = 135/105
Subtract the two like fractions:
147/105 - 135/105 = 147 - 135/105 = 12/105
After reducing the fraction, the answer is 4/35

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