Answer:
The two numbers are 6 and 12.
Explanation:
So, let's start off, with x+y = 18 and x-y = 6.
Algebraically, we can add the above two equation sets, and we find out that 2x = 24, so x = 12. And then, it says the other number must be 6.
You start with a number that when added to the second number you will get 18 and when you subtract the second number from the first you will get 6. The difference between the above two results is 12.
So that difference of 12 is twice the second number; that means the second number is 6. And then using either of the given pieces of information, you can find that the first number is 12.
------------------------------------------------------
In conclusion:
6 + 12 = 18
12 - 18 = 6