Subtract 15/21 from 21/90, Solve 21/90

Subtract 15/21 from 21/90

21/90 - 15/21 is -101/210.

Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 90 × 7 = 630,
21/90 = 21 × 7/90 × 7 = 147/630
Likewise, for the 2nd fraction, since 21 × 30 = 630,
15/21 = 15 × 30/21 × 30 = 450/630
Subtract the two like fractions:
147/630 - 450/630 = 147 - 450/630 = -303/630
After reducing the fraction, the answer is -101/210

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