Tính nhanh

Bài 16: Tính nhanh
a) 3/4 + 2/5 + 1/4 + 3/5
b) 2/3 x 3/4 x 4/5 x 5/6
c) 4/5 - 2/3 + 1/5 - 1/3
d) 4/5 x 3/7 + 4/5 x 4/7
e) 2/5 x 7/4 - 2/5 x 3/7
h) 13/4 x 2/3 x 4/13 x 3/2
i) 975/100 + 18/21 + 19/32 + 1/4 + 3/21 + 13/32
g) 2/5 + 6/9 + 3/4 + 3/5 + 1/3 + 1/4