What two numbers add to 9 and multiply to 168?

Let's denote the two numbers as x and y. From the given conditions, we have the following system of equations:

x + y = 9 xy = 168

By solving the first equation for y (y = 9 - x) and substituting it into the second equation, we get:

x(9 - x) = 168 9x - x^2 = 168 x^2 - 9x + 168 = 0

Factoring the quadratic equation gives us (x - 8)(x - 21) = 0. Therefore, the two numbers are 8 and 21.