Answer:
10
Step-by-step explanation:
This triangle is isosceles, same as the little triangle.
If one side of the little triangle is 3x, then the little side with the tick (let's name it a) is also 3x.
That means the longer side, 2a, is 6x
This triangle is isosceles, so 6x = 4x + 20
Now, if we solve that, x = 10
The answer is 10
Hope this helps :)
Have a good day!
