Answer
\$160 for the permit.
Work Step by Step
Split the difference between the two firms.
Price = average of the two marginal costs:
$P=\frac{MC_H+MC_L}{2}=\frac{190+130}{2}=160$
So the price of a permit is \$160.
H buys at \$160 → pays less than \$190 → gains \$30 per permit.
L sells at \$160 → receives more than \$130 → gains \$30 per permit.
