first multiply -20 by 3:
x^2+7x-60
then break down the factors of 60:
1,60 2,30 3,20 4,15 5,12 6,10
next figure out which factors multiply to =60 and subtract to equal 7
12-5=7 12*5=60
then you have:
(x+12)(x-5)
then see if 12 and 5 can be divided by 3 (12 can, 5 cant so you'd get the following)
(x+4)(3x-5)
then set both equal to 0 and solve
x+4=0 x=-4
3x-5=0 3x=5 x=5/3
the factors are {-4,5/3}
