Answer:
That exterior angle is equal to 87 degrees.
Explanation:
In order to find the measure of the exterior angle, we start by trying to find x. We can do this by adding up the 3 interior angles and setting them equal to 180. The first angle is equal to 43. The second angle is equal to x + 15. The third angle is equal to 180 - 3x (which we know because the angle and 3x is equal to 180). So we set equal to 180.
43 + (x + 15) + (180 - 3x) = 180 ----> Combine like terms.
238 - 2x = 180 -----> Subtract 238
-2x = -58 ----> Divide by -2
x = 29
Now that we have the x value, we can plug into the exterior angle measure to get the value.
3x = 3(29) = 87 degrees