#### Answer

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

#### Work Step by Step

$12x^{2}$ - x -20 = (4x+5) (3x__)
step 1. Find two first terms whose product is $12x^{2}$
$12x^{2}$ - x -20 = (4x+5) (3x__) which is given and
Step 2. To find the second term of each factor, we must find two integers whose product is -20 and whose sum is -1
List pairs of factors of the constant, -20
(1,-20)(-1,20)(-4,5)(4,-5)(2,-10)(-2,10)
step 3. The correct factorization of $12x^{2}$ - x -20 is the one in which the sum of the Outside and Inside products is equal to -x.
list of the possible factorization :
(4x+5)(3x-4) = $12x^{2}$ - x -20
(4x-5)(3x+4) = $12x^{2}$ + x -20
So, (4x+5)(3x-4) is the solution