Answers

Add 54/21 and 42/40

1^st number: 2 12/21, 2^nd number: 1 2/40

54/21 + 42/40 is 507/140.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 40 is 840
   
   Next, find the equivalent fraction of both fractional numbers with denominator 840
2. For the 1st fraction, since 21 × 40 = 840,
   54/21 = 54 × 40/21 × 40 = 2160/840
3. Likewise, for the 2nd fraction, since 40 × 21 = 840,
   42/40 = 42 × 21/40 × 21 = 882/840
4. Add the two like fractions:
   2160/840 + 882/840 = 2160 + 882/840 = 3042/840
5. 3042/840 simplified gives 507/140
6. So, 54/21 + 42/40 = 507/140
   In mixed form: 387/140

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