Question 461890
x - y = 3 and xy = 54

==> y = x - 3
==> x(x - 3) = 54

<==> {{{x^2 - 3x - 54 = 0}}}
<==> (x - 9)(x + 6) = 0
==> x = 9, -6.  Discard -6.
==> One number is 9, and the other number is x - 3 = 9 - 3 = 6.