What adds up to 3 and multiplies to 108?

Answer 1

Nine and twelve. 12 x 9 = 108, 12 + (-9) = 3

If you want a better answer, try to solve the equations a*b=108, a+b=3 by substitution. Simply plug in b=3-a for b in a*b=108 to get -a*a+3*a-108=0. Then note the discriminant is negative, showing there are no (real) solutions.

If you can use more than two numbers, try -3, -2, 2, 3, 3