Question 972136
C = rate of current 
so basically you are cross multiplying {{{10/(9+c) = 5/(9-c)}}}
cross multiply {{{10*(9-c)}}} 
which equals {{{90-10c}}} 
cross multiply {{{(9+c)*5}}} 
which equals {{{45+5c}}}
{{{90-10c = 45+5c}}} 
{{{90-45 = 45}}}
{{{10c+5c = 15c}}}
{{{45 = 15c}}}
{{{45/15 = c}}}
{{{3=c}}} 
the answer for rate of current is 3