Hello, Jiyongie!

Your function is off . . . but you were close.

In planning a restaurant, it is estimated that a profit of $6 per seat will be made

if the number of seats is no more than 50, inclusive.

On the other hand, the profit on each seat will decrease by 10¢ for each seat above 50.

a) Find the number of seats that will produce the maximum profit.

Let = number of seats in excess of 50.

There will be: . seats.

Then each seat brings a profit of: . dollars.

Therefore: .