Subtract 70/9 from 90/40, Solve 2 10/40

Subtract 70/9 from 90/40

1^st number: 2 10/40, 2^nd number: 7 7/9

90/40 - 70/9 is -199/36.

Find the least common denominator or LCM of the two denominators:
LCM of 40 and 9 is 360

Next, find the equivalent fraction of both fractional numbers with denominator 360
For the 1st fraction, since 40 × 9 = 360,
90/40 = 90 × 9/40 × 9 = 810/360
Likewise, for the 2nd fraction, since 9 × 40 = 360,
70/9 = 70 × 40/9 × 40 = 2800/360
Subtract the two like fractions:
810/360 - 2800/360 = 810 - 2800/360 = -1990/360
After reducing the fraction, the answer is -199/36

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