Subtract 25/20 from 4/81, Solve 4/81

Subtract 25/20 from 4/81

1^st number: 4/81, 2^nd number: 1 5/20

4/81 - 25/20 is -389/324.

Find the least common denominator or LCM of the two denominators:
LCM of 81 and 20 is 1620

Next, find the equivalent fraction of both fractional numbers with denominator 1620
For the 1st fraction, since 81 × 20 = 1620,
4/81 = 4 × 20/81 × 20 = 80/1620
Likewise, for the 2nd fraction, since 20 × 81 = 1620,
25/20 = 25 × 81/20 × 81 = 2025/1620
Subtract the two like fractions:
80/1620 - 2025/1620 = 80 - 2025/1620 = -1945/1620
After reducing the fraction, the answer is -389/324

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