The behavior of the annual maintenance and repair cost in the Bus Transportation Department of the Summerset Public School District is shown by the solid line in the following graph. The dashed line depicts a semivariable-cost approximation of the department's repair and maintenance cost. Exercis Approximati Cost; Public (LO 6-1, 6-2 Monthly repair and maintenance cost $4,000 $3,000 $2,000 $1,000 10 20 20 30 40 40 50 Actual cost (curvilinear) Approximation (semivariable) Thousands of 60 60 70 80 90 100 miles driven