What is the value of x?

x = 84 degrees

Step-by-step explanation:

To solve this, we need to keep the following 2 things in mind:

a. A straight line will have an angle of 180 degrees.

b. A triangle's inside angles will have a sum of 180 degrees.

Knowing the first fact, we know that the unnamed angle to the left in the triangle PLUS the 143 degree angle, will equal 180.

143 + v = 180

I'm calling that angle v here.

Subtracting 143 from both sides:

v = 180 - 143 = 37

That angle is 37 degrees.

Now, our 2nd fact says that all inside angles in a triangle will add to 180.

Angle 1 = 59 degrees (bottom right)

Angle 2 = 37 degrees (bottom left)

Angle 3 = x (top)

59 + 37 + x = 180

96 + x = 180

Subtracting 96 from both sides:

x = 84

x = 84 degrees