For this case we find the number of yards for each second that runs each and compare:

Then, the difference is:
\frac {44} {5} - \frac {50} {7} = \frac {308} {35} - \frac {250} {35}
\frac {44} {5} - \frac {50} {7} = \frac {58} {35}
While Juan runs \frac {50} {7} yards per second, Amy runs \frac {44} {5} yards per second. Amy is faster, runs \frac {58} {35} yards per second faster than Juan.
Answer:
Amy is faster, runs \frac {58} {35} yards per second more than Juan.