Add 21/42 and 90/20, Solve 21/42 + 4 10/20 as a fraction

Add 21/42 and 90/20

1^st number: 21/42, 2^nd number: 4 10/20

21/42 + 90/20 is 5/1.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 42 × 10 = 420,
21/42 = 21 × 10/42 × 10 = 210/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
90/20 = 90 × 21/20 × 21 = 1890/420
Add the two like fractions:
210/420 + 1890/420 = 210 + 1890/420 = 2100/420
2100/420 simplified gives 5/1
So, 21/42 + 90/20 = 5/1

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