speed of the car

Question

A car went 2 hours with a constant speed and then spent 3 hours in a jam moving 20 mi/h slower than before. During the next 2 hours, the car moved 10 mi/h faster than during the first two hours of its journey. Find the speed of the car during the first two hours of its journey, if it is known that the car has travelled 380 miles.

Answer 1

distance=rate*time

380=r*2+(r-20)*3+(r+10)*2

380=2r+3r-60+2r+20

380=7r-40

380+40=7r

420=7r

r=420/7

r=60 miles per hour during the first 2 hours