2m-3mn-2n/m-2mn-n=[m-mn-n+(m-2mn-n)]/m-2mn-n
=1+m-mn-n/m-2mn-n
m-mn-n/m-2mn-n=[(1/n)-1-(1/m)]/[(1/n)-2-(1/m)]
=[(-3)-1]/[(-3)-2]=4/5
1+m-mn-n/m-2mn-n
=1+4/5=9/5.