1/48除以(5/12+5/8-1/6-3/4)=1/48*12/5+1/48*8/5-1/48*6-1/48*4/3=1/20+1/30-1/8-1/36=1/4-1/5+1/5-1/6-1/2(1/2-1/4)-1/36=1/4-1/5+1/5-1/4+1/8-1/36=1/8-1/36=1/4*1/2-1/4*1/9=1/4(1/2-1/9)=1/4*7/18=7/72