The answer would be 19
Range is basically just taking the highest and lowest number which in this case is 61 and 42 and then subtracting which gives you 19. Hope this helps!
You divide 90/60 which is an hour and you get 1.5 and you multiply that by 8..... which is 12 gallons.
To find the volume, you would do base x width x height.
Using this information, what can you conclude?