Hi Caitlynn,
I assume you mean to create a sum of 20 that meets your description.
If we use the variable x to represent one of the numbers, then we can represent the other as: x - 6
Next we can write an equation and solve it if we know that are two numbers should "make" 20:
x + x - 6 = 20
2x - 6 = 20
2x - 6 + 6 = 20 + 6
2x = 26
2x/2 = 26/2
x = 13
The second number will be x - 6 or 13 - 6 = 7
The two numbers are 13 and 7 .
Hope this helps. Let me know if you have more questions or would like to schedule a session (online if you prefer).
Take care.
Mrs. R.