I want to help you find the answer for the question that you are asking for but you just said find the length of the missing side and there is no numbers or picture for me to help you please upload a picture with the question so that I can help you....
The amount of water that is turned in a minute is 5.2d. Given the fact that initially was 350 gallons of water everything you pour needs to be added to the initial amount. So the answer is V(x) = 350+5.2x (D). I hope that this is the answer that you were looking for and it has helped you.
