Subtract 2/21 from 20/40
20/40 - 2/21 is 17/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 21 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 40 × 21 = 840,
20/40 = 20 × 21/40 × 21 = 420/840 - Likewise, for the 2nd fraction, since 21 × 40 = 840,
2/21 = 2 × 40/21 × 40 = 80/840 - Subtract the two like fractions:
420/840 - 80/840 = 420 - 80/840 = 340/840 - After reducing the fraction, the answer is 17/42
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