(1)3x/5-2/5=1/6
移项:3x/5=2/5+1/6
=12/30+5/30
=17/30
所以x=17/30÷(3/5)
=17/30* 5/3
=17/18
(2)3x/4+3x/2=17
9x/4=17
x=17÷(9/4)
x=68/9
(3) 4x/7+1/9÷5/12=4/5
4x/7=4/5-4/15
4x/7=8/15
x=14/15
(4)2/5(x+12)=8
2x/5=8-2/5*12
2x/5=16/5
x=.8
①移项得3x/5=-7/30
所以x=-7/18
②通分得9x/4=17
x=68/9
③即4x/7 4/15=4/5
移项得4x/7=8/15
所以x=14/15
④两边同时乘以5得
2x 24=40
所以x=8