math
posted by victor .
During each shift as a bus driver, Haley drives between 80 and 140 miles. She started the month with 4,500 miles driven.
What is a reasonable estimate for the number of total miles she has driven the bus, after 20 more shifts?

Assuming some average mileage, I'd say she drives about 110 miles each shift.
So, she'll have about 4500 + 20*110 = 4500 + 2200 = 6700 miles