Subtract 21/20 from 16/45, Solve 16/45

Subtract 21/20 from 16/45

1^st number: 16/45, 2^nd number: 1 1/20

16/45 - 21/20 is -25/36.

Find the least common denominator or LCM of the two denominators:
LCM of 45 and 20 is 180

Next, find the equivalent fraction of both fractional numbers with denominator 180
For the 1st fraction, since 45 × 4 = 180,
16/45 = 16 × 4/45 × 4 = 64/180
Likewise, for the 2nd fraction, since 20 × 9 = 180,
21/20 = 21 × 9/20 × 9 = 189/180
Subtract the two like fractions:
64/180 - 189/180 = 64 - 189/180 = -125/180
After reducing the fraction, the answer is -25/36

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