Question

what is the value of x? 20 35 60 70

Explanation:

Step1: Identify angle - relationship

The two angles $(x + 40)^{\circ}$ and $(3x)^{\circ}$ are vertical angles. Vertical angles are equal.
So we set up the equation $x + 40=3x$.

Step2: Solve the equation

Subtract $x$ from both sides:
$x - x+ 40=3x - x$
$40 = 2x$.
Then divide both sides by 2:
$\frac{40}{2}=\frac{2x}{2}$
$x = 20$.

Answer:

A. 20