There is an acute angle that is 29 degrees and an obtuse angle that is (x-5) degrees. We also 180, which is half of a circle. ( whole circle would be 360 degrees).
Our equation is 180 = (x-5)+29
180 = (x-5)+29
-29 -29
151 = x-5
+5 +5
156 = x
I know I didn't explain this well, but I hope at leat you understand a little bit.