Answers

Subtract 18/72 from 21/70

21/70 - 18/72 is 1/20.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 70 and 72 is 2520
   
   Next, find the equivalent fraction of both fractional numbers with denominator 2520
2. For the 1st fraction, since 70 × 36 = 2520,
   21/70 = 21 × 36/70 × 36 = 756/2520
3. Likewise, for the 2nd fraction, since 72 × 35 = 2520,
   18/72 = 18 × 35/72 × 35 = 630/2520
4. Subtract the two like fractions:
   756/2520 - 630/2520 = 756 - 630/2520 = 126/2520
5. After reducing the fraction, the answer is 1/20

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