(3/4-2/3)÷1/5=(9/12-8/12)X5=1/12X5=5/12(3/8-7/12)X8+1/17=3/8X8-7/12X8+1/17=3-14/3+1/17=5/3+1/17=88/514/5X7/8+7/8÷5=4/5X7/8+7/8X1/5=(4/5+1/5)X7/8=1X7/8=7/8(1-8/15X3/4)÷3/5=(1一2/5)X5/3=3/5X5/3=1