Subtract 21/12 from 42/25, Solve 1 17/25

Subtract 21/12 from 42/25

1^st number: 1 17/25, 2^nd number: 1 9/12

42/25 - 21/12 is -7/100.

Find the least common denominator or LCM of the two denominators:
LCM of 25 and 12 is 300

Next, find the equivalent fraction of both fractional numbers with denominator 300
For the 1st fraction, since 25 × 12 = 300,
42/25 = 42 × 12/25 × 12 = 504/300
Likewise, for the 2nd fraction, since 12 × 25 = 300,
21/12 = 21 × 25/12 × 25 = 525/300
Subtract the two like fractions:
504/300 - 525/300 = 504 - 525/300 = -21/300
After reducing the fraction, the answer is -7/100

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