Answer:
x = 12
Step-by-step explanation:
140 + x = 180
-140 -140
x = 40
A triangle sums up to 180 degrees so add all of the sides
40 + (3x + 4) + (8x + 4) = 180
Add all like terms
48 + 11x = 180
-48 -48
11x = 132
Divide
