You need to go from point A to point B, and then back to point A. Points A and B are 20 miles apart. You go to point B at a constant speed of 15 miles per hour. If you want your overall speed to be 30 miles per hour, how fast would you have to go from point B back to point A?

(In reply to

re: solution by Richard)

man you are brilliant

hats off to you

i could jus simply say that at 15 miles an hour the distance of 20 miles will be covered in an hour and 20 min

whereas to gain a speed of 30 miles an hour over a distance of 40 miles (20+20) we need an hour and 20 min so even at the speed of light its not possible

i agree with your ans on infinity

thank you