Subtract 42/49 from 21/90, Solve 21/90

Subtract 42/49 from 21/90

21/90 - 42/49 is -131/210.

Find the least common denominator or LCM of the two denominators:
LCM of 90 and 49 is 4410

Next, find the equivalent fraction of both fractional numbers with denominator 4410
For the 1st fraction, since 90 × 49 = 4410,
21/90 = 21 × 49/90 × 49 = 1029/4410
Likewise, for the 2nd fraction, since 49 × 90 = 4410,
42/49 = 42 × 90/49 × 90 = 3780/4410
Subtract the two like fractions:
1029/4410 - 3780/4410 = 1029 - 3780/4410 = -2751/4410
After reducing the fraction, the answer is -131/210

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