Answer:
1/3
Explanation:
Given that two lines are perpendicular.
Slope of green line (one of the lines) is -3.
To find the slope of other perpendicular line red.
We know that angle between two lines with slopes m1 and m2 would be

where m1 is the slope of I line and m2 slope of second line.
Here since two lines are perpendicular angle between them is 90 degrees and hence we get infinity as tan x
this implies denominator for
=0
i.e. 1+m1m2 = 0
Or m1m2 =-1
Since one of slope m1 = -3 we have
-3m2= (-1) or m2 = 1/3