Subtract 28/80 from 21/70
21/70 - 28/80 is -1/20.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 80 is 560
Next, find the equivalent fraction of both fractional numbers with denominator 560 - For the 1st fraction, since 70 × 8 = 560,
21/70 = 21 × 8/70 × 8 = 168/560 - Likewise, for the 2nd fraction, since 80 × 7 = 560,
28/80 = 28 × 7/80 × 7 = 196/560 - Subtract the two like fractions:
168/560 - 196/560 = 168 - 196/560 = -28/560 - After reducing the fraction, the answer is -1/20
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