Subtract 36/40 from 70/21, Solve 3 7/21

Subtract 36/40 from 70/21

1^st number: 3 7/21, 2^nd number: 36/40

70/21 - 36/40 is 73/30.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 21 × 40 = 840,
70/21 = 70 × 40/21 × 40 = 2800/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
36/40 = 36 × 21/40 × 21 = 756/840
Subtract the two like fractions:
2800/840 - 756/840 = 2800 - 756/840 = 2044/840
After reducing the fraction, the answer is 73/30
In mixed form: 213/30

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