This is the last question I need help with

The sum of two numbers is 12 and their difference is 18 what are the two numbers

Which expression shows the sum of the polynomials with like terms grouped together

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?