Subtract 21/84 from 90/72, Solve 1 18/72

Subtract 21/84 from 90/72

1^st number: 1 18/72, 2^nd number: 21/84

90/72 - 21/84 is 1/1.

Find the least common denominator or LCM of the two denominators:
LCM of 72 and 84 is 504

Next, find the equivalent fraction of both fractional numbers with denominator 504
For the 1st fraction, since 72 × 7 = 504,
90/72 = 90 × 7/72 × 7 = 630/504
Likewise, for the 2nd fraction, since 84 × 6 = 504,
21/84 = 21 × 6/84 × 6 = 126/504
Subtract the two like fractions:
630/504 - 126/504 = 630 - 126/504 = 504/504
After reducing the fraction, the answer is 1/1

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