Subtract 90/72 from 12/30, Solve 12/30

Subtract 90/72 from 12/30

1^st number: 12/30, 2^nd number: 1 18/72

12/30 - 90/72 is -17/20.

Find the least common denominator or LCM of the two denominators:
LCM of 30 and 72 is 360

Next, find the equivalent fraction of both fractional numbers with denominator 360
For the 1st fraction, since 30 × 12 = 360,
12/30 = 12 × 12/30 × 12 = 144/360
Likewise, for the 2nd fraction, since 72 × 5 = 360,
90/72 = 90 × 5/72 × 5 = 450/360
Subtract the two like fractions:
144/360 - 450/360 = 144 - 450/360 = -306/360
After reducing the fraction, the answer is -17/20

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