The monthly high and low levels of direct labor hours and of total manufacturing overhead for Monyx Company are as shown: Highest observed level Lowest observed level Direct Labor Mfg Hours Overhead 8.000 $34.000 4.000 $26.000 On the basis of the above data, the cost formula for Monyx's monthly manufacturing overhead can be expressed as: O $18.00 average cost per direct labor hour. O $1.80 average cost per direct labor hour. $26,000 fixed cost plus $1.50 per direct labor hour. $18,000 fixed cost plus $2.00 per direct labor hour