Subtract 21/24 from 30/42, Solve 30/42

Subtract 21/24 from 30/42

30/42 - 21/24 is -9/56.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 24 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 42 × 4 = 168,
30/42 = 30 × 4/42 × 4 = 120/168
Likewise, for the 2nd fraction, since 24 × 7 = 168,
21/24 = 21 × 7/24 × 7 = 147/168
Subtract the two like fractions:
120/168 - 147/168 = 120 - 147/168 = -27/168
After reducing the fraction, the answer is -9/56

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