Subtract 21/42 from 10/45, Solve 10/45

Subtract 21/42 from 10/45

10/45 - 21/42 is -5/18.

Find the least common denominator or LCM of the two denominators:
LCM of 45 and 42 is 630

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 45 × 14 = 630,
10/45 = 10 × 14/45 × 14 = 140/630
Likewise, for the 2nd fraction, since 42 × 15 = 630,
21/42 = 21 × 15/42 × 15 = 315/630
Subtract the two like fractions:
140/630 - 315/630 = 140 - 315/630 = -175/630
After reducing the fraction, the answer is -5/18

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