5/14÷20/21× 3/4 [2-(1/2-1/3]×6/5
= 5/14×21/20×3/4 =[2-(3/6-2/6]×6/5
= 1/2×3/4×3/4 =11/6×6/5
=9/32 =11/5
5/6÷3/4+1/6÷3/4 4/5÷[(3/4-1/2)×4/5]
= (5/6+1/6)×4/3 =4/5÷(1/4×4/5)
=4/3 =4/5×5 =
=4
(2/3+1/4)÷3/8 4/5÷(1/5+4/15)
= 11/12×8/3 =4/5×15/7
= 22/9 =12/7
(5/8+5/12)×4/15
=25/24×4/15
=5/18