Question

What two numbers multiply to 20 and add to -12?

Answer 1

a • b = 20
a - b = -12

Answer 2

Solve this system of equations. (you can use substitution)

Answer 3

-2 multiplied by -10 is 20. -2+ (-10) = -12.

Answer 4

Better yet, you can guess.

Make a list of all factors of 20 using only negative factors.
Then add each pair of factors until you find the correct pair.

Negative Sum of
Factors of 20 Factors
-1, -20 -21 ---> sum does not work
-2, -10 -12 ---> here it is on the second try
-4, -5 -9 ---> done just for completeness