Subtract 98/80 from 21/70, Solve 21/70

Subtract 98/80 from 21/70

1^st number: 21/70, 2^nd number: 1 18/80

21/70 - 98/80 is -37/40.

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,
98/80 = 98 × 7/80 × 7 = 686/560
Subtract the two like fractions:
168/560 - 686/560 = 168 - 686/560 = -518/560
After reducing the fraction, the answer is -37/40

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