Suppose the numbers are a and b
You are given that a-b=20 and a+b=14
So adding these we get,
[tex]a - b + a + b = 20 + 14[/tex]
[tex]2a = 34[/tex]
[tex]a = 17[/tex]
You are given that a-b 20 therefore
[tex]17 - b = 20[/tex]
[tex]b = 20 - 17[/tex]
[tex]b = 3[/tex]
Hope it helps you