Each firm emits 100 units of carbon

Abatement costs per unit for each firm are

...$200 per unit for Ford

...$150 per unit for Toyota

...$100 per unit for GM

...$50 per unit for Honda

If 200 tradeable permits are auctioned what will be the equilibrium price of the permits? Who will buy the permits? Are abatement costs minimized?

Now suppose the government sets a carbon tax equal to $125. Who will pay the tax? Are abatement costs minimized?