How many gallons of warter is in 35 feet by 42 feet by 3 inches?
The tricky thing about this question is the different units of
measure. You have gallons, feet, and inches, and they can't work
together until you make some conversions.
The easiest conversion would be to make all your linear
dimensions into feet (since inches get large quickly, and nobody
likes cubic inches). Since there are 12 inches in a foot, we
convert the short side by doing 3 inches / 12 inches = .25 feet.
Now we can find the volume of the rectangular prism: 35 ft * 42 ft
* .25 ft = 367.5 cubic feet.
Great. But you want to know how much water this hold in gallons,
not cubic feet. However, the two are both units of volume, so there
must be a conversion between the two. A quick Google search reveals
that 1 cubic foot = 7.4805 US gallons. So now all you need to do is
multiply both sides of that equation by your total cubic feet,
which is 367.5.