Subtract 3/7 from 21/45, Solve 21/45

Subtract 3/7 from 21/45

21/45 - 3/7 is 4/105.

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,
3/7 = 3 × 45/7 × 45 = 135/315
Subtract the two like fractions:
147/315 - 135/315 = 147 - 135/315 = 12/315
After reducing the fraction, the answer is 4/105

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