Question

find the value of two numbers if their sum is 18 and their difference is 2

Answer 1

8 and 10 are the two values

Answer 2

Let X be the first and second number.
    X+X = 18
+  X-X = 2
      2X = 20 (divide both sides by 2
      X   = 10
Substitute the values to get the second number
   10+X = 18
         X = 18 -10
         X = 8
Therefore, the numbers are 10 and 8