4) Robert was reviewing the water bill for his carwash business and determined that the highest bill, $5,200, occurred in July when 2,200 cars were washed and the lowest bill, $3,100, occurred in February when 1,500 cars were washed. What was the variable cost per carwash? A) $2.36 B) $1.41 C) $3.00 D) $2.07