the smaller number is 13 and the larger one is 18.
Let's say that the smaller number is x and the larger one is y.
Giving the equation x + 5 = y
This would also make the equation y^2-x^2= 155
to solve let's simplify to find what y^2 is in x terms.
y^2 = (x+5) (x+5) = x^2 +10x + 25.
therefore x^2 + 10x + 25 -x^2= 155
10x + 25 = 155
10x = 130
x = 13
y = 18