Resposta :
a) 5/7 - 2/3
mmc
7 , 3 3
7 , 1 7
1 , 1 / 3 . 7 = 21
3.5/21 - 7.2/21
15/21 - 14/21
1/21
b) 3/5 + 1/2
mmc
5 , 2 2
5 , 1 5
1 , 1 / 2 . 5 = 10
2.3/10 + 5.1/10
6/10 + 5/10
11/10
c) (-1/8) + (-7/8)
-1/8 - 7/8
-8/8
-1/1
-1
d) (+1/5) + (+3/5)
4/5
e) (-1/3) + (-1/5)
mmc
3 , 5 3
1 , 5 5
1 , 1 / 3 . 5 = 15
5 . (-1/15) + 3 . (-1/15)
-5/15 + (-3/15)
-5/15 - 3/15
-8/15
f) (-47) - (-37)
(-47) + 37
-10