Suppose one factory produces residential windows and doors. The following scenarios describe various straight-line production possibility boundaries for this factory. Each scenario describes the numbers of doors that could be produced in one day if all the factory's resources were devoted to producing doors and the number of windows that could be produced in one day if all the factory's resources were devoted to producing windows. For each scenario, calculate the opportunity cost to the factory owner of producing one extra door.

a. 900 windows; 225 doors

The opportunity cost to the factory owner of producing one extra door is

____ window(s).(Round your answer to two decimal places.)