Subtract 20/21 from 42/45
42/45 - 20/21 is -2/105.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 21 is 315
Next, find the equivalent fraction of both fractional numbers with denominator 315 - For the 1st fraction, since 45 × 7 = 315,
42/45 = 42 × 7/45 × 7 = 294/315 - Likewise, for the 2nd fraction, since 21 × 15 = 315,
20/21 = 20 × 15/21 × 15 = 300/315 - Subtract the two like fractions:
294/315 - 300/315 = 294 - 300/315 = -6/315 - After reducing the fraction, the answer is -2/105
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