Subtract 15/30 from 4/21, Solve 4/21

Subtract 15/30 from 4/21

4/21 - 15/30 is -13/42.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 30 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 21 × 10 = 210,
4/21 = 4 × 10/21 × 10 = 40/210
Likewise, for the 2nd fraction, since 30 × 7 = 210,
15/30 = 15 × 7/30 × 7 = 105/210
Subtract the two like fractions:
40/210 - 105/210 = 40 - 105/210 = -65/210
After reducing the fraction, the answer is -13/42

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