Twenty seven minus ten plus four
There are many ways you can do this. To me, the easiest way is cross multiplying, but since the denominators are the same, there is no need to do that. Also, the fractions are negatives, the one closest to 0 is closer to the surface of the pool
-4/5 = -2/5 in this case -2/5 is closer to the surface of the pool.
Answer: the boy's feet are closer to the surface of the pool
I suppose you mean

Substitute y = √(9 + x). Solving for x gives x = y² - 9, so that 9 - x = 18 - y², and we have differential dx = 2y dy. Replacing everything in the integral gives

Simplify the integrand by dividing:


For the first term of this new integral, we have the partial fraction expansion


The rest is trivial:



