Question

How can i find the angle of HEI

Answer 1

So you know that angle I is verticle angles to the 60 degrees angle
And you known that the verticloe angle to 20 is an important part 
Then you use the sum of interior angles formula 
which is all the angles in the triangle should add up to 180

20 + 60 + m< HEI = 180
80 + m< HEI = 180
  -80                    -80

m< HEI = 100 

I believe the measure of the angle is 100, I hope it makes sense too!