Please DO NOT post complete solution when the OP has shown NO EFFORT.b)
(x+y, y, x+2y)=(2m , m+3 , 0)
x+y=2m
y=m+3
x+2y=0
From the 3rd x=-2y
Subbing on the first
-2y+y=2m
-y=2m
looking that with the 2nd and adding them together
y=m+3
-y=2m
0=3m+3
m=-1