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