Subtract 3/40 from 18/21, Solve 18/21

Subtract 3/40 from 18/21

18/21 - 3/40 is 219/280.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 21 × 40 = 840,
18/21 = 18 × 40/21 × 40 = 720/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
3/40 = 3 × 21/40 × 21 = 63/840
Subtract the two like fractions:
720/840 - 63/840 = 720 - 63/840 = 657/840
After reducing the fraction, the answer is 219/280

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