ECON 101 · Chapter 9 · Lecture

Where did the gains
from trade go?

Four buyers want one repair each. Four sellers can each do one repair. A tax changes the prices they face. Find the repairs that still happen, then follow the gains from trade.

1 of 4 · Start with the trades

Before the tax

Each buyer's value (willingness to pay, or WTP) is the highest price they would pay. Each seller's cost includes the resources and time used for a repair. At a market price of $5.50, how many repairs will be bought and sold?

Predict completed repairs
Model assumptions and prices

This hypothetical competitive market has no externalities, tax collection costs or administration costs. Each person trades at most one repair. Rows are efficient marginal pairings, not mandatory partners. Reservation values do not change when the tax changes.

Discrete clearing prices can lie in an interval. The displayed prices are valid clearing prices, not unique predictions. Tax revenue counts dollar for dollar in total surplus; benefits of government spending are outside this account. This exercise alone does not settle real tax policy.