Question 763213
Recheck your book to review these rules about logarithms:


{{{highlight(log(a*b)=log((a))+log((b)))}}}


{{{highlight(log(a/b)=log((a))-log((b)))}}}


TRUST those rules.  Your given expression, {{{log(x)/log(7)-log(y)}}} which seems to be according to how you showed it, the ratio of logarithms MINUS another logarithm.  I believe you cannot condense that into a single logarithm.  


You may try this way:
{{{log(x)/log(7) -(log(y))(log(7)/log(7))=(log(x)-log(7)log(7))/log(7)}}} but this does not help.


Again, as said, you showed ratio of two logs minus another log.  No rule for that.  Are you SURE that your original expression was as you wrote?