765 / 9 = 85
9*100 = 900 but this is too much
900 - 765 = 135
9 goes into 135 15 times (9*10=90 which leaves 45 which is 9*5 so 5+10) so you minus 15 from the 100 that made 900
so 100 - 15 = 85
C is the answer to you question
For this case we must indicate which of the equations shown can be solved using the quadratic formula.
By definition, the quadratic formula is applied to equations of the second degree, of the form:

Option A:

Rewriting we have:

This equation can be solved using the quadratic formula
Option B:

Rewriting we have:

It can not be solved with the quadratic formula.
Option C:

Rewriting we have:

This equation can be solved using the quadratic formula
Option D:

Rewriting we have:

It can not be solved with the quadratic formula.
Answer:
A and C
Here is the answer
I did it with steps
3a+2(4a-1)=9
3a+8a-2=9
11a=11
a=1