Find two numbers whose difference is 15 and whose product is 1584

X - y = 15

Xy = 1584

We'll use substitution to solve. Let's manipulate the first equation.

X = y + 15

Now we can plug in y + 15 for x in the second

Y (Y + 15) = 1584

Y^2 + 15Y = 1584

You can now solve this like any quadratic. I'll complete the square.

(Y + 7.5) ^2 = 1640.25

Y + 7.5 = 40.5

Y = 33

X - 33 = 15

X = 48