∵m-3n+1=0
∴m-3n=-1

4﹙m-3n﹚²-m+3n-5﹙m-3n﹚²-7
＝4﹙m-3n﹚²-(m-3n)-5﹙m-3n﹚²-7
=-(m-3n)²-(m-3n)-7
=-(-1)²-(-1)-7
=-1+1-7
=-7