How do you factor when "a" is greater than 1? pls show work pls show work so i can understand 4 x^2 - 7x - 15

For
if a≠1 then
first seee if you can undsitribute a
ifyou can't
use the ac method

multiply a and c
find 2 numbers that add to b and multiply to get ac
split b into that
group
undistribute
undistribute

so


ac=4*-15=-60
what 2 numbers multiply to get -60 and add to get -7?
5 and -12
split b up into -12 and 5

group

undistribute

undistribute

Set square i think so

Ithink the answer is c