Tính: 1/2.(-3/4).(-5/8).(-8/9)

a) 1/2 . -3/4 . -5/8 . -8/9
b) 3/8 - ( 3/4-1/2 )
c) 23/27 - -5/21 - 4/23 + 1/2 +16/21
d) 7/8 : 5/4 . -10/7
e) 6/5 + 1/6 : (-3)
f) -2/3 - -3/4 + 1/6 - 1/2
h) 8/9 + 1/9 . 2/9 + 1/9 .7/9
i) 240 . 1/3 - 240 . 0,5 + 1/6 .240
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