Distance = velocity x time Assume the distance moved by your friend is "d" and that the time taken for you to catch to him is "t"
you are moving with a velocity of 18 mph and your friend is moving with a velocity of 12 mph. distance covered by your friend (d) = 12t miles ......> equation 1
If you add 3 to your rate, your distance will be the same as your friend's. This means that: <span> d+3 = 18t miles ......> equation 2
Substitute by 1 in 2: 12t + 3 = 18t 3 = 6t t = 0.5 hours This means that you will catch up to your friend in half an hour.</span>
