First find the other side of the 115° (to form a 180° angle) .. so 180-115=65°. Now since you have a 65° and 85° in a triangle...then you can add them and subtract the sum from 180 to get the third angle in the triangle. Because 3 angles in a triangle HAVE to equal up to 180°. So 65+85=150..180-150=30°.
Now, since you have the 30° angle (the angle located to the left of the right angle shown in the picture)...you can now find the angle to the right of the right angle. Since all of those 3 angles form a straight angle; then all of them has to equal up to 180°. So 30+90=120...180-120=60°. Now you have 60° at the right of the right angle (shown in the picture). You then want to find the other side of the 155° angle, to form a straight angle. So 180-155=25°. So now, you have a 25° and 60° in the other triangle. So add them up and subtract the sum from 180 to get the third angle. so 60+25=85°...180-85=95°. Now you have the third angle...which is located above the "x" that you are trying to find. Since the 95° and the "x" forms a straight angle...you can just subtract 95° from 180 to get "x". So 180-95=85°.
X= 85° :)
