Subtract 81/21 from 40/70
1st number: 40/70, 2nd number: 3 18/21
40/70 - 81/21 is -23/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 21 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 70 × 3 = 210,
40/70 = 40 × 3/70 × 3 = 120/210 - Likewise, for the 2nd fraction, since 21 × 10 = 210,
81/21 = 81 × 10/21 × 10 = 810/210 - Subtract the two like fractions:
120/210 - 810/210 = 120 - 810/210 = -690/210 - After reducing the fraction, the answer is -23/7
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