Answer:
yes
Step-by-step explanation:
rearrange the equations
x+y+7=0 &
x-y+20=0
find out slopes of the lines
which is -a/b
for the first one it is
-1/1=-1
and for the second
-1/-1=1
find the product of the slopes
-1×1 = -1
since the product of the slopes is -1
the lines are perpendicular
