Express the sum of each pair of numbers as a product of the greatest common factor and another sum 42 + 105

hello from mrbilldoesmath!

answer:

x - 3

discussion:

x^2 - 9 = (x-3) (x+3)   so

(x^2-9)/ (x + 3) = x-3

you,

mrb

if you was gonna solve for a, a is a   < -12