Subtract 15/20 from 21/54, Solve 21/54

Subtract 15/20 from 21/54

21/54 - 15/20 is -13/36.

Find the least common denominator or LCM of the two denominators:
LCM of 54 and 20 is 540

Next, find the equivalent fraction of both fractional numbers with denominator 540
For the 1st fraction, since 54 × 10 = 540,
21/54 = 21 × 10/54 × 10 = 210/540
Likewise, for the 2nd fraction, since 20 × 27 = 540,
15/20 = 15 × 27/20 × 27 = 405/540
Subtract the two like fractions:
210/540 - 405/540 = 210 - 405/540 = -195/540
After reducing the fraction, the answer is -13/36

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