Need Help with some algebra

I have a problem that gives me this info:

a 17 inch across circular hole
2.5 bags of concrete is used
each bag makes 1800 inches^3
I need to find the depth of the hole


Also need help with this

How much water should be added to 14 mL of an 8% alcohol solution to make it a 7% solution?

Please show me the steps to solve them. Thanks!!

Im doing this in reverse order....
2) 14x.08=1.12
That means that there is 1.12 ml of alcohol in the fluid.
So if 1.12 is 7% of a substance. Then 1.12/x=7/100
then 7x=112
then x=16-final answer.
1) if the diameter of the hole is 17 inches, then the areais Pi(8.5(the radius)^2)
Area=226.865 in^2
If each bag has a volume of 1800 inches^3, then the total volume of the hole is 1800 x 3 5400 inches to the third dimension. So you take 5400/226.865. Which equals 23.8027 inches deep

Only know first one.

The formula to find the volume of a cylinder is V = height x pi x radius^2
Your volume is 2.5 x 1800, which is 4500in^3
pi is 3.14
So 4500 = height x 3.14 x radius^2

You have diameter, 17 in. radius is 1/2 diameter, which is 8.5 inches.

4500 = height x 3.14 x 8.5^2

divide 4500 by (3.14 x 8.5^2) and you get 7.9

Check work
Does 7.9 x 3.14 x 8.5^2 equal 4500?
Yup