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

1A)

A company finds that it can sell 80 items at a price of $140 each and sell 100 items at a price of $90 each.

D(x) =

1B)

A company finds that at a price of $90 each it can sell 100 items. If the price is raised $30, then 20 fewer items are sold.