What two numbers multiplies to -225 but adds to 16

Give the 2 numbers variables,say x and y.
then they multiply to -225.this means xy=-225
they add to 16.this means x+y=16
                                               y=16-x

substitute y=16-x onto xy=-225 to get x(16-x)=-225
then expand to get 16x-x^2=-225
rearrange to get a quadratic: x^2-16x-225=0
                                              x=(16+(16^2-4*-225)^0.5))/2 or 
                                              x=(16-(16^2-4*-225)^0.5))/2