Question 4879
There is only one variable, since you only need to find one unknown quantity.  I think you meant to ask, "If we sell 252 tickets, then how many people are in the group?"  Am I right? 


Let x = the number people in the group.

Your sentence says 9% of the members buy tickets (which equals 252), so 
{{{.09 * x = 252}}}


To solve for x, you need to divide both sides by .09:
{{{(.09*x)/.09 = 252/.09}}}


Next, multiply numerator and denominator by 100 to clear the decimal from the denominator.
{{{ x = 25200/9 = 2800}}} people in the group.


R^2 at SCC