One hour after Matthew started waking from r to y, a distance of 45km, Johnny started walking along the same road from y to r. Matthew's walking rate was 3 km per hour and Johnny's was 4km per hour, how many km had Johnny walked when they met?
Choose the correct choice.
A) 24  B) 23  C) 22  D) 21  E) 19.5
Just an alternative method...   After the first hour the distance r is 42 km (45-3). Now the problem can be treated as if bothof them started at the same time. Since the speeds are in the ratio 3 : 4, the distances will also be in the same ratio. Splitting 42 in that ratio we get 18 : 24. So answer is 24.   Hence 24.
<result>A</result>
One hour after Matthew started waking from r to y, a distance of 45km, Johnny started walking along the same road from y to r. Matthew's walking rate was 3 km per hour and Johnny's was 4km per hour, how many km had Johnny walked when they met?