2x-3/5=2/3x-2
2x-2/3x=-2+3/5
4/3x=-7/5
x=-21/20
代入3n-1/4=3(x+n)-2n得
3n-1/4=3(-21/20+n)-2n
3n-1/4=-63/20+3n-2n
2n=-63/20+1/4
n=-29/20题是这样；（2x-3）÷5＝（2/3）x-2.后面按原题做（2x-3）÷5＝（2/3）x-2

3(2x-3)=15[(2/3)x-2]
6x-9=10x-30
x=21/4

代入3n-1/4=3(x+n)-2n得
3n-1/4=3(21/4+n)-2n
3n-1/4=63/4+3n-2n
2n=63/4+1/4
n=8

(n-3)^2=5^2=25