
The answer is above.
Additional note 1:

Additional note 2:
In the answer I filled in "0" at the place where "n" was. This is because the question tells us n=0
let the consecutive multiples be 7(n-1) , 7n and 7(n+1)
so 7(n-1)+7n+7(n+1)=777
or 3n=111,
n=37
252,259,266
A is the answer because x^2-6x-7 is (x-7)(x+1).