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The total cost of an office dinner was shared equally by k of the n employees who attended the dinner. What was the total cost of the dinner?
1) Each of the k employees who shared the cost of the dinner paid $19.
2) If the total cost of the dinner had been shared equally by k + 1 of the n employees who attended the dinner, each of the k + 1 employees would have paid $18.

Both the Statements together are necessary.

Let total cost be X.

Statement 1 : X = 19*k

Statement 2 : X = 18(k+1)

Solving for k, k=18

Hence X, total cost = 19*18