Let the two numbers be x and y.
The sum of two numbers is 20. So we can write:
x + y = 20
The difference of two numbers is 14. So we can write:
x - y = 14
Adding the two equations, we get:
2x = 34
⇒
x = 17
Using the value of x in 1st equation we get:
17 + y = 20
⇒
y = 3
So the two numbers are 17 and 3.