Answer:
40 degrees and 140 degrees
Explanation:
To solve this problem you can add x+3x+20 and set that equal to 180. (We can do this because angle x and angle 3x + 20 make a linear pair. Knowing this we can estimate that both angles added together will equal 180)
Let us add x + 3x + 20 = 180 to find x. We can then substitute that into the equation.

a: So in this part, we have rewritten the equation to make it easier to solve
b: In this step, you combine the like terms x+3x to get 4x
c: In step c, you are subtracting 20 from both sides to keep constants on one side and variables on the right
d: In this last step the equation has been simplified to make it easier to solve.
e: To isolate x you have to divide both sides by 4, we do this because the coefficient of x is 4 so you divide the equation by 4 to cancel it out.
f: You rewrite and simplify the equation.
Now to find the measure of both angles you substitute x into the equation.
The first angle's value is 40 degrees and the second is 140 degrees.
These are our answers.