Answer:
x = 25 degrees
Explanation:
All the angles in a triangle must add up to 180 degrees.
That means: 2x + 15 + x + 10 + 3x + 5 = 180
Collect the like terms and put it on one side and put the whole numbers on the other.
2x + x + 3x = 180 - 15 - 10 - 5
6x = 150
x = 25