Add 28/21 and 21/72, Solve 1 7/21 + 21/72 as a fraction

Add 28/21 and 21/72

1^st number: 1 7/21, 2^nd number: 21/72

28/21 + 21/72 is 13/8.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 72 is 504

Next, find the equivalent fraction of both fractional numbers with denominator 504
For the 1st fraction, since 21 × 24 = 504,
28/21 = 28 × 24/21 × 24 = 672/504
Likewise, for the 2nd fraction, since 72 × 7 = 504,
21/72 = 21 × 7/72 × 7 = 147/504
Add the two like fractions:
672/504 + 147/504 = 672 + 147/504 = 819/504
819/504 simplified gives 13/8
So, 28/21 + 21/72 = 13/8
In mixed form: 15/8

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