Use the figure below to answer Questions $[12][13]$

$[12]$ Using the figure above, suppose the Steel firm is producing at its profit maximizing level. What is the total external cost imposed on the Laundry business?

$[13]$ Using the figure above, if the Steel firm was granted the right to pollute, what payment would the Laundry firm have to make to the Steel firm to motivate the efficient level of steel production?