<span>We have to calculate the length of the missing side.
Use the Pythagorean theorem:


I think. Your answers to choice are wrong.
</span>
Answer:
the would be 85.7 %
you would do 66/77 which is .857142857
then move the decimal point two spots and round then you'll get 85.7 %
Value of x is 9
As when we multiply a + 3 by -2a2 + 15a + 6
We get
(a + 3) (-2a2 + 15a + 6)
-2a3 + 15a2 + 6a - 6a2 + 45a + 18
-2a3 + 9a2 + 51a + 18
If we compare the coefficients of a2, we get
x = 9