Could you maybe walk me through this Algebra word problem?

Question

Here is the problem:

Anita wants to put a moat around her rectangular castle. The castle is 45 ft by 60 ft. Let m be the width of the moat.

1. Write a polynomial that represents the total area of the castle and moat.

2. Find the combined area if the moat is 10 feet wide.

3. If the moat is also 10 feet deep, calculate how many gallons of water are in the moat is 1 gallon (almost) = 0.134 ft (cubed). Round the answer to the gallon.

I'm just kinda lost. If you can show me how this problem is done, I'd be really grateful.

Answer 1

If the moat has width m,

castle area = 45*60 = 2700
castle+moat area = (45+2m)(60+2m)
since there is moat on both sides.
moat area = (45+2m)(60+2m)-2700

Now plug in your value for m, and recall that volume is area * depth

Answer 2

2500ft^2 x 1gal/(0.134ft^2)=~ 186567 gal. Right?

Answer 3

your answer is right, but your units are not The volume is

2500 ft^2 * 10 ft = 25000 ft^3

25000 ft^3 * 1gal/(0.134 ft^3) = 186567 gal

Answer 4

That's right.. sorry 'bout that. Thanks, Mate.