3+1/4X=17 ==> 1/4X=17-3 ==> X=14*4=56X-0.2X=16 ==> 0.8X=16 ==> x=16/0.8=20X除3/4=2/9 ==> X=2/9*(3/4)=1/61/4+1/2X=15 ==>1/2X=15-1/4=(15*4-1)/4 ==> 1/2X=59/4 ==>X=(59/4)*2=59/2(其中==>表示的是推出下一步...