I am not positive on this but I believe the answer is 600/15 because you can then accurately see how many feet the submarine rises per hour.
Volume= length x width
So the length and width are 13 so 13x13= 169 but it says ROUND to the nearest whole number so 169 rounded to the nearest whole number is 170. So your answer is 170. I hope this helps
You can set up an equation such as 300=100+8x where x is equal to the number of days gone by since birth. The answer would be 25 days.