Answer :
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
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
first you do -225+16 which equals -209
then you dived it by 2 which is not a whole number
then you go to 3 - no
4 - no
5 -no
6-no
7-no
8-no
9-no
10 - no
11 - yes
so theequation is
11* (-19) +16 = -225