Members of a club each contributed equally to obtain $1800 for a holiday trip. When 6 members found that they could not go, their contributions were refunded and each remaining member then had to pay $10 more to raise the $1800. How many went on the trip?
number of people going originally ---- n
cost per person = 1800/n
6 quit, so now there are n-6
refund to those 6 = 6(1800/n)
new share = 1800/n + 10 , this is paid by n-6
(n-6)(1800/n + 10) = 1800
1800 + 10n - 10800/n - 60 = 1800
every term times n, the 1800 will cancel
10n^2 - 60n - 10800 = 0
n^2 - 6n - 1080 = 0
solve for n using your favourite method to solve a quadratic