Answer:
Well supplementary means that both the angles add up to 180 
We know that the measure of angle 3 is 13 degrees. 
The measure of angle 4 is unknown 
And the total of angles 3 and 4 are 180. 
So you can make an equation
13 + x = 180 
Solve for x 
x= 167 
Measure of angle 4 is 167 
m< 4 = 167 degrees