Simearl, Welcome to TFP!! :-D
Of course Evan (Waterbear) is right! I just ran the numbers and (assuming that the shallow end is 18 X 30 and from the 'break' to the deep end is 18 X 28 with a constant slope and flat bottomed hopper) get the following:
18 * 30 = 540
540 * 3 = 1620
1620 * 7.5 = 12,150
18 * 28 = 504
504 * 5.5 = 2772
2772 * 7.5 = 20, 790
20,790 + 12,150 = 32,940 so call it 33,000 gal and you should be pretty close.
If the reason for calculating is to add chems, be sure to
underdose the pool! These calculations have a good bit of 'slop' in them and it's easier to have to add chems in 2 doses than to overshoot your mark and have to add another chem, or worse - drain some water and refill, to bring the levels back down.
Again, welcome to the forum

- we'll be here if you have any more questions