问数学高手们几道简算题！！求求大家，我急死了，你们真的快点吧，谢谢啦，别忘了过程哦

①（7/12*3/4-1/3）*4/5
=（7/4×1/4-1/3）×4/5
=（7/16-1/3）×4/5
=7/16×4/5-1/3×4/段局5
=7/逗皮20-4/15
=21/60-16/60
=5/60
=1/12
②3/4*5/14+3/10÷12
=15/56+1/10×1/4
=15/56+1/40
=75/280+7/280
=82/280
=41/140
③（3/7-3/7*7/山燃差8）÷1/2
=（3/7-3/8）×2
=（1/7-1/8）×3×2
=（8/56-7/56）×6
=1/56×6
=6/56
=3/28

①（7/12*3/4-1/3）*4/5
=（21/48-16/48）*4/5
=5/48*4/此源5
=1/12

②3/4*5/14+3/10÷12
=3/4*5/14+3/10*1/12
=15/56+1/谨扒猛40
=75/祥桥280+7/280
=82/280=41/140

③（3/7-3/7*7/8）÷1/2
=（3/7-3/8）/2
=3/56/2
=3/112

①原题＝（7/亮森16-1/者瞎3）×4/5
＝5/首键空48×4/5
＝1/12