Subtract 21/18 from 7/40, Solve 7/40

Subtract 21/18 from 7/40

1^st number: 7/40, 2^nd number: 1 3/18

7/40 - 21/18 is -119/120.

Find the least common denominator or LCM of the two denominators:
LCM of 40 and 18 is 360

Next, find the equivalent fraction of both fractional numbers with denominator 360
For the 1st fraction, since 40 × 9 = 360,
7/40 = 7 × 9/40 × 9 = 63/360
Likewise, for the 2nd fraction, since 18 × 20 = 360,
21/18 = 21 × 20/18 × 20 = 420/360
Subtract the two like fractions:
63/360 - 420/360 = 63 - 420/360 = -357/360
After reducing the fraction, the answer is -119/120

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