How fast was Brian driving?

Question

After their final exam, brian and alex leave campus at the same time. Brian drives 8 mph faster than alex, and at one point, brian has driven 12 miles and alex has driven 10 miles. How fast was brian driving?

Answer 1

Let A = Alex's rate and B = Brian's

B = A+8

The trick here is to notice that each has driven the same amount of time

and remember rate*time= distance

12/(A+8) = 10/A

12A = 10A + 80

You should be able to finish it from here!