Pg 635 (567) - Q20
This is a madeup functions problem. Using the definition of
#, we get the statements x = 5a and y = 5b.
xy would then equal 5a * 5b. Since you can
add the exponents when the terms have the same base, this would equal 5a+b,
and substituting 3 for a+b, you
would get 53, or 125, choice D.