Consider a market with network? externalities, where demand is Q = 100 - 1P.
Let price initially be $40, where current demand without network externalities would be Q1 = 80.00 - .50P.
Suppose the price falls to $30, where demand without network externalities would be Q2 = 85.00 - .50P.
With network? externalities, the price change increases the quantity demanded by ___ units.