Question 377402
Let x +6 = original number of kids.  So x = remaining number of kids after 6 left.

Then {{{1800/x - 1800/(x+6) = 10}}},
or
{{{180/x - 180/(x+6) = 1}}}, or
{{{0 = x^2 + 6x - 1080}}}, after simplification.
(x-30)(x+36) = 0.
Thus there are x = 30 kids going to the trip.