Question

What is the value of x

Answer 1

x = 21

Explanation:

Sum of interior angles in a triangle = 180

3x + x - 4 + 100 = 180

4x + 96 = 180

4x = 84

x = 21

Answer 2

The three inside angles of a triangle need to equal 180 degrees.

One angle is given as 100, so the other two need to equal 180-100 = 80 degrees.

So now you have:

x-4 + 3x = 80

Combine like terms"

4x - 4 = 80

Add 4 to each side:

4x = 84

Divide both sides by 4:

x = 84/4

x = 21