Answer:
x=12
Explanation:
This is an equilateral triangle. That means all the angles are equal
There are three angles and they add to 180. 180/3 =60. Each angle is equal to 60
4x+12 =60
Subtract 12 from each side
4x+12-12 = 60-12
4x = 48
Divide by 4
4x/4 =48/4
x=12