Question 26982
{{{260/x-260/(x+13)=1}}}
260[(x)-(x+13)=(x)(x+10)
{{{260(13)=x^2+13x}}}
{{{x^2+13x-3380=0}}}
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
a=1, b=13, c=-3380
{{{x=(-13+-sqrt((13)^2-4(1)(-3380)))/(2*1)}}}
{{{x=(-13+-sqrt(169+13520))/(2)}}}
{{{x=(-13+-sqrt(13689))/(2)}}}
{{{x=(-13-117)/(2)}}} or {{{x=(-13+117)/(2)}}}
x=-65 or x=52


Remove the negative x=52.
Hence, the speed of the bus is 52km/h.
Paul.