Hello, there!
4 * x = 4x
4 * 5 = 20
Now, we have 3 + 4x + 20 = 31
Now, let's combine like terms.
3 and 20 are like terms.
3 + 20 = 23
Now, we have 4x + 23 = 31
Now, let's isolate the x.
4x + 23 = 31
-23 -23
4x = 8
FInally, we will simplify this.
4x = 8
--- ----
4 4
x = 2
Our final answer is x = 2
I hope I helped!
Let me know if you need anything else~
~ Zoe