Question 38790
The smaller pipe takes x+5 
And the other pipe takes x hours to fill the tank.
EQUATION:
{{{1/x+1/(x+5)=(1)/(10/3)}}}
{{{((x)+(x+5))=(3((x)(x+5)))/10}}}
{{{2x+5=(3x^2+15x)/10}}}
{{{20x+50=3x^2+15x}}}
{{{3x^2-5x-50=0}}}
Factor you get :
x=5 
5+5=10
Hence, one pipe takes 5 hours and other takes 10 hours to fill the tank.
Paul.