Answer:

Explanation:
We have been given with the quadratic equation 
We have general formula to find the roots of a quadratic equation first we find the discriminant with formula

and after that to find the variable suppose x we have the formula

And general quadratic equation is

On comparing the given quadratic equation with genral quadratic equation we will have values
a=1, b=-7 and c=-6
After substituting these values in the formula we will get

After substituting in the formula to find x we will get

The recipricol of -2/9 is 9/2, or 4 1/2
remember to change the sign (forgot to myself)
hope this helps
Tha number one the aswer is b 5.4
A) 0 represents the surface of the pool.
B) The height of the pool is 10 above the pool surface
C) It should be -3 since it is going down so it is going to be a negative number and it is also below the pool's surface.
Four times a number is equal to negative eight.