I am struggling with this problem from GMATPrep test:
To celebrate a colleauge's retirement, T coworkers in an office agreed to share equally the cost of catered lunch.
If lunch costs X dollars and S of coworkers fail to pay their share, which of the following represents the additional amount, in dollars, that each of the remaining coworkers would have to contribute so that the cost of lunch is completely paid?
Since no absolute values are given in the question we can replace the given parameters with assumed numbers,
Let Total colleagues be 100 (T)
Let total contribution be 500 (X) (point to note is that its total cost not per person)
Those who dont pay are S (30)
Per person cost = X/T = 500/100 = 5
So cost for those who failed to pay = (X/T) * S = SX/T = 30*5=150
The equation for people who would bear the total cost after S people fail = (T-S)=70
There fore the solution is (SX/T)/ (T-S) = SX/T(T-S) = 150/70
Hope this helps !!!
CONSIDER AWARDING KUDOS IF MY POST HELPS !!!