8/15×3/4-1/6÷1/2=2/5-1/6x2=2x(1/5-1/6)=1/15
5/4×5/6+1/6×5/4=5/4×（5/6+1/6）=5/4×1=5/4
32.6×4/5+32.6×20%=32.6X（4/5+1/5)=32.6x1=32.6