a) 2/3 + 1/5 . 10/7
= 2/3 + 2/7
= 14/21 + 6/21
= 20/21
b) -5/18 + 5/9 - 11/36
= 5/18 - 11/36
= 10/36 - 11/36
= -1/36
c) -3/7 + 15/26 + (-2/13 + 3/7)
= -3/7 + 15/26 + 25/91
= 27/182 + 25/91
= 27/182 + 50/182
= 11/26
d) -7/11 . 11/19 + -7/11 . 8/19 - 4/11
= -7/11 . (11/19 + 8/19) - 4/11
= -7/11 . 1 - 4/11
= -7/11 - 4/11
= -28/121
e) -5/9 + 5/9 : (3 và 1/3 - 1 và 2/3)
= 0 : 5/3
= 0
f) 2/7 + 5/7 . (3/5 - 0,25) . (-2)^2 + 35%
= 2/7 + 5/7 . (3/5 - 1/4) . 4 + 7/20
= 2/7 + 5/7 . 7/20 . 4 +7/20
= 2/7 + 1/4 . 4 + 7/20
= 2/7 + 1 + 7/20
= 9/7 + 7/20
= 229/140
g) -4/5 . 11/13 + 4/5 . (-2/13) - 1/5
= -4/5 . 11/13 - (-4/5) . (-2/13) - 1/5
= -4/5 . (11/13 - (-2/13)) - 1/5
= -4/5 . 1 - 1/5
= -4/5 - 1/5
= -1