I know the answer to this problem is

-3x^2 +10x - 9

my problem is understanding this step the way i would work it out gives the answer -3x^2 + 10x - 3 which is wrong.

my understanding is the sign is always stuck to the number when grouping like terms.

-3x^2 - 3 + 10x - 6

=

(group like terms)

-3x^2 + 10x - 3 - 6

=

-3x^2 + 10x - 3

any help would be great cheers guys