Subtract 72/7 from 21/45, Solve 21/45

Subtract 72/7 from 21/45

1^st number: 21/45, 2^nd number: 10 2/7

21/45 - 72/7 is -1031/105.

Find the least common denominator or LCM of the two denominators:
LCM of 45 and 7 is 315

Next, find the equivalent fraction of both fractional numbers with denominator 315
For the 1st fraction, since 45 × 7 = 315,
21/45 = 21 × 7/45 × 7 = 147/315
Likewise, for the 2nd fraction, since 7 × 45 = 315,
72/7 = 72 × 45/7 × 45 = 3240/315
Subtract the two like fractions:
147/315 - 3240/315 = 147 - 3240/315 = -3093/315
After reducing the fraction, the answer is -1031/105

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