Subtract 21/70 from 18/72
18/72 - 21/70 is -1/20.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 72 and 70 is 2520
Next, find the equivalent fraction of both fractional numbers with denominator 2520 - For the 1st fraction, since 72 × 35 = 2520,
18/72 = 18 × 35/72 × 35 = 630/2520 - Likewise, for the 2nd fraction, since 70 × 36 = 2520,
21/70 = 21 × 36/70 × 36 = 756/2520 - Subtract the two like fractions:
630/2520 - 756/2520 = 630 - 756/2520 = -126/2520 - After reducing the fraction, the answer is -1/20
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