Angles in a triangle always add up to 180 degrees
Here, we add up all the angles given to equal it to 180 degrees:
X + X + 10 + X + 5 = 180
Collect like terms -> 3X + 10 + 5 = 180
Add the whole numbers -> 3X + 15 = 180
Take 15 from to the other side (then make it negative) to isolate the X:
3X = 180 - 15
The subtract -> 3X = 165
Take 3 over to the other side (and it it should divide 165) and isolate the X -> X = 165/3
Finally, X = 55
Now wherever you see X in the triangle, replace it with 55.
With that, the top angle = 55 + 10 = 65 degrees
The bottom left angle = 55 + 5 = 60 degrees
The bottom right angle = 55 degrees
