What two numbers add up to 45 and multiply and get 121

Let the two numbers be x and y.

We have x+y=45
⇒ y= 45-x.

The two numbers multiply and get 121, so we have another equation:
x*y = 121 (1)

Plug y= 45-x in (1), we have:
x* (45-x)=121
⇒ 45x - x^2 = 121 (distributive property)
⇒ x^2 - 45x = -121 (multiply -1 on both sides)
⇒ x^2- 45x + 121= 0
⇒ x= 42.128 or x= 2.872

y= 45- 42.128= 2.872
or y= 45- 2.872= 42.128.

Because it does not matter what number, x or y, is larger, the two numbers are 2.872 and 42.128.

Hope this helps~