(3/4-1/8)÷1/24=(3/4-1/8)×24=3/4×24-1/8×24=18-3=151/7X6/13+8/13÷7=6/(7×13)+8/(7×13)=14/(7×13)=2/131/5÷[(2/3+1/5)X1/13]=1/5÷[13/15X1/13]=1/5÷1/15=1/5×15=3