Q1. Find the demand equation using the given information. (Let x be the number of items.)

A company finds that it can sell 60 items at a price of $80 each and sell 110 items at a price of $20 each.

D(x) = ?

Q2. A builder needs to rent a dump truck for a day for $70 plus $0.80 per mile. Find the cost function. (Let x be the number of miles.)

C(x) = ?

Q3. The cost function for a species of wild fish is estimated to be a function C(x) where x is the number of millions of pounds of this fish caught and C is the cost in millions of dollars. Two points that are on the graph are (x, C) = (4, 0.1638) and (x, C) = (7, 0.231). Using this information and assuming a linear model, determine a cost function.

C(x) = ?