Internal company records. That's the answer if you need me to explain it just tell me, hope it was helpful. Peace✌️
The number of each type of book is what is unknown, so we can represent those quantities with variables. Let x = the number of hardbacks and y = the number of paperbacks. Then we know that: x + y = 65 (the total number of books sold) We also know the total cost of both editions, which is $1356. It can be written algebraically as: 28x + 12y = 1356 We now have a system of two equations, which can be solved by substitution. It would be easier to solve the first equation for either x or y and substitute that into the second equation.
In the context of the promotional mix, personal selling attempts to persuade the buyer to accept a point of view. Personal selling is when a sales rep meets with a potential client to close the sale. Personal selling describes in person sales events that help promote the potential client while informing them of the product.
The cost of underestimating the demand is considered a revenue loss that arises due to cancellation of flight costing $134. Hence, cost of underetimating the demand is

.
The cost of overestimating the demand is known as rewards. For example, free round trip ticket worth $263. Hence, the cost of overestimating the demand is

.

The z-score that yields a p-value of 0.3375 is -0.4193.
Thus, super discount airlines should overbook the flight by 35 + (-0.4193 x 24) = 35 - 10.0632 = 24.9368 = 25 seats.
Therefore, super discount airlines should overbook the flight by 25 seats.