Current Attempt in Progress

At the high level of activity in November, $12000$ machine hours were run and power costs were $$18000.$ In April, a month of low activity, $4000$ machine hours were run and power costs amounted to $$9000.$ Using the high$-$low method, the estimated fixed cost element of power costs is

$$4500$

$$18000$

$$9000$

$$13500$