5/6*3/8+5/6*5/8=(5/6)*(3/8+5/8)=(5/6)*1=5/64/7*(14+7/9) =(4/7)/14+(4/7)*(7/9)=8+4/9=8又9分之42÷(3/5*2/3)=2÷(2/5)=2*(5/2)=515÷(5/12+5/6)=15÷(5/12+10/12)=15÷(15/12)=15*(12/15)=12