Question 301459
Playing with my calculator, I found that
{{{2401 = 7^4}}}
{{{log(7, 7^4) = 4}}}
And I found that 
{{{243 = 3^5}}}
{{{log(3,3^5) = 5}}}
so,
{{{log(7,2401) - log(3,243) = 4 - 5}}}
{{{4 - 5 = -1}}} answer