Subtract 18/20 from 7/81
7/81 - 18/20 is -659/810.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 20 is 1620
Next, find the equivalent fraction of both fractional numbers with denominator 1620 - For the 1st fraction, since 81 × 20 = 1620,
7/81 = 7 × 20/81 × 20 = 140/1620 - Likewise, for the 2nd fraction, since 20 × 81 = 1620,
18/20 = 18 × 81/20 × 81 = 1458/1620 - Subtract the two like fractions:
140/1620 - 1458/1620 = 140 - 1458/1620 = -1318/1620 - After reducing the fraction, the answer is -659/810
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