Ask me math

it is simple, just look for those numerical values which on multiplication give -20*3 = -60

and on addition give +7

they are 12 and -5

so rewrite quadratic as

3x^2 + 12x - 5x -20 = 0

3x(x+4) -5(x+4) = 0

(3x-5)(x+4) = 0

x = 5/3 and x = -4 answer