Question

What is the value of x?

Answer 1

Well first you have to set the two equal to each other
x+40=3x, then subtract x from both sides
40=2x, then divide both by two to get x alone
x=20

Answer 2

They are vertically opposed angles.

They are equal!

So x+40 = 3x and we solve it -> x-3x = -40 -> -2x = -40 -> 2x=40 so x = 20