Subtract 9/40 from 12/42
12/42 - 9/40 is 17/280.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 42 × 20 = 840,
12/42 = 12 × 20/42 × 20 = 240/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
9/40 = 9 × 21/40 × 21 = 189/840 - Subtract the two like fractions:
240/840 - 189/840 = 240 - 189/840 = 51/840 - After reducing the fraction, the answer is 17/280
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