Bunuel wrote:

If Tom and Huckleberry working at their respective rates can each whitewash 600 square feet of fence in x and y hours, respectively, how long will it take both of them working together at their own rates to whitewash 600 square feet of fence?

(1) x - y = 1

(2) (xy)/(x + y) = 6/5

\(\frac{600}{x} + \frac{600}{y}= \frac{600(x + y)}{xy}\)

A. \(x - y = 1\) => \(y = x- 1\)

\(\frac{600(x + x-1)}{x(x + 1)}\) = \(\frac{600(2x-1)}{x^2 + x}\)

A is insufficient because we don't know a value of xB. \(\frac{xy}{(x+y)} =\frac{6}{5}\) => \(\frac{(x+y)}{xy}\) = \(\frac{5}{6}\) = \(\frac{1}{1.2}\)

\(\frac{600(x + y)}{xy}\) = \(\frac{600*1}{1.2}\)

B is sufficient it will take 1.2 hours to finish the job