What is negative 4 greater than or less than x?

The vet charges $45 for an office visit and $10 for each vaccination your dog needs. write an eaquation

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. how many hours after the truck's departure will the two meet?

Which expression do you get when you eliminate the negative exponents of 4a^2 b^216a^-3 b