Tucker Pups Pet Resort offers dog boarding services in Chicago. Assume that in March, when dog-days occupancy was at an annual low of 150 days, the average cost per dog-day was $65. In July, when dog-days were at a capacity level of 600, the average cost per dog-day was $20. (a) Develop an equation for monthly operating costs. Total cost = $? + $? * X (b) Determine the average boarding cost per dog-day at an annual volume of 4,500 dog-days. $?