Subtract 90/40 from 2/21, Solve 2/21

Subtract 90/40 from 2/21

1^st number: 2/21, 2^nd number: 2 10/40

2/21 - 90/40 is -181/84.

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,
2/21 = 2 × 40/21 × 40 = 80/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
90/40 = 90 × 21/40 × 21 = 1890/840
Subtract the two like fractions:
80/840 - 1890/840 = 80 - 1890/840 = -1810/840
After reducing the fraction, the answer is -181/84

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