AirQual Test Corporation provides on$-$site air quality testing services. The company has provided the following cost formulas and actual results for the month of February:

The company uses the number of jobs as its measure of activity. For example, mobile lab operating expenses should be $$4,900$ plus $$31$ per job, and the actual mobile lab operating expenses for February were $$9,390.$ The company expected to work $150$ jobs in February, but actually worked $154$ jobs.