Subtract 70/45 from 42/21, Solve 2 0/21

Subtract 70/45 from 42/21

1^st number: 2 0/21, 2^nd number: 1 25/45

42/21 - 70/45 is 4/9.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 45 is 315

Next, find the equivalent fraction of both fractional numbers with denominator 315
For the 1st fraction, since 21 × 15 = 315,
42/21 = 42 × 15/21 × 15 = 630/315
Likewise, for the 2nd fraction, since 45 × 7 = 315,
70/45 = 70 × 7/45 × 7 = 490/315
Subtract the two like fractions:
630/315 - 490/315 = 630 - 490/315 = 140/315
After reducing the fraction, the answer is 4/9

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