Subtract 70/21 from 28/30, Solve 28/30

Subtract 70/21 from 28/30

1^st number: 28/30, 2^nd number: 3 7/21

28/30 - 70/21 is -12/5.

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

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 30 × 7 = 210,
28/30 = 28 × 7/30 × 7 = 196/210
Likewise, for the 2nd fraction, since 21 × 10 = 210,
70/21 = 70 × 10/21 × 10 = 700/210
Subtract the two like fractions:
196/210 - 700/210 = 196 - 700/210 = -504/210
After reducing the fraction, the answer is -12/5

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