Question 449535
Let {{{x}}} = original number of players + coach
{{{ 540/x}}} = original amount each had to pay
{{{ 540 = (540/x + 1.5)*(x-5) }}}
{{{ 540 = 540 + 1.5x - 2700/x - 7.5 }}}
{{{ 2700/x + 7.5 = 1.5x }}}
{{{ 2700 + 7.5x = 1.5x^2 }}}
{{{ 1.5x^2 - 7.5x - 2700 = 0 }}}
{{{ x^2 - 5x - 1800 = 0 }}}
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
{{{x = (-(-5) +- sqrt( (-5)^2-4*1*(-1800) ))/(2*1) }}} 
{{{x = ( 5 +- sqrt( 25 + 7200 )) / 2 }}} 
{{{x = ( 5 +- sqrt( 7225 )) / 2 }}} 
{{{x = ( 5 + 85) / 2 }}}  ( can't use negative square root )
{{{ x = 45 }}}
{{{ x - 5 }}} people made the trip
{{{ 45 - 5 = 40 }}}
40 people made the trip
check:
{{{ 540 = (540/x + 1.5)*(x-5) }}}
{{{ 540 = (540/45 + 1.5)*(45-5) }}}
{{{ 540 = ( 12 + 1.5)* 40 }}}
{{{ 540 = 13.5*40 }}}
{{{ 540 = 540 }}}
OK