Question

efetue 1/2+1/5
1/3+1/4
2/3+3/5+1/6

Answer 1

1/2 + 1/5 = (5+2)/(5x2) = 7/10
2/3 + 3/5 + 1/6 = ...
mmc (2,5,6) = 30
(30:3.2)/30 + (30:5.3)/30 + (30:6.10/30 = 
20/30 + 18/30 + 50/30 = (20+18+50)/30 = 88/30 ou 44/15 (simplificando)

Answer 2

a) 1/2 + 1/5 = (mmc 10) = (5 + 2)/10 = 7/10

b) 1/3 + 1/4 = (mmc 12) = (4 + 3)/12 = 7/12

c) 2/3 +3/5 +1/6 = (mmc = 30) = (20 + 18 + 5)/30 = 43/30

Espero ter ajudado.