Answer:
A letter (can be mostly any letter) given that has an unknown quantity to it. X is a very common letter to use.
Step-by-step explanation:
For example, 4 + X = 5 (This is just an easy equation to make am explanation more understandable.)
You have to figure out how much x is worth. The answer is 1 because 4 × 1 = 5. Sometimes, you may even see a number multiplying to the variable. Like, 4x=16. When a variable is next to a number like that, that means you are multiplying. 4 times what equals 16? Well, it's 4. So X equals 4.
