Answer:
x = 21
Step-by-step explanation:
We know that a triangle equals to 180 degrees.
Combine like terms. (x + 3x) and (-4 + 100)
x - 4 + 3x + 100 = 180
Subtract 96 on both sides.
4x + 96 = 180
-96 -96
Divide 4 on both sides.
4x = 84
--- -----
4 4
And you get a solution of 21.
x = 21
Check:
Substitute 21 into x.
Add/Subtract from left to right.
21 - 4 + 3(21) + 100 = 180
17 + 63 + 100 = 180
80 + 100 = 180
180 = 180
