Subtract 9/40 from 15/42, Solve 15/42

Subtract 9/40 from 15/42

15/42 - 9/40 is 37/280.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 42 × 20 = 840,
15/42 = 15 × 20/42 × 20 = 300/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
9/40 = 9 × 21/40 × 21 = 189/840
Subtract the two like fractions:
300/840 - 189/840 = 300 - 189/840 = 111/840
After reducing the fraction, the answer is 37/280

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