6÷3/8-3/8÷6 =6×8/3-3/8x1/6=16-1/16=16又16分之15 4/7x5/9+3/7x5/9 =5/9x(4/7+3/7)=5/9x1=5/9 5/2-(3/2+4/5) =5/2-3/2-4/5=1-4/5=1/5 7/8+(18+1/8)=7/8+18+1/8=19 9x5/6+5/6=5/6x(9+1)=5/6x10=25/3 3/4x8/9-1/3=2/3-1/3=1/3