(2x-m)/4-1/2=(x-m)/3
x=1/2代入得:
(1-m)/4-1/2=(1/2-m)/3
m=5
1/4(-4mm+2m-8)-(1/2 m-1)
=1/4(-100+10-8)-(1/2*5-1)
=-49/2-3/2
=-26