Subtract 6/21 from 9/40, Solve 9/40

Subtract 6/21 from 9/40

9/40 - 6/21 is -17/280.

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

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 40 × 21 = 840,
9/40 = 9 × 21/40 × 21 = 189/840
Likewise, for the 2nd fraction, since 21 × 40 = 840,
6/21 = 6 × 40/21 × 40 = 240/840
Subtract the two like fractions:
189/840 - 240/840 = 189 - 240/840 = -51/840
After reducing the fraction, the answer is -17/280

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