One hour after Matthew started waking from w to y, a distance of 45km, Johnny started walking along the same road from y to w. 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?	Options:
A) 24
B) 23
C) 22
D) 21
E) 19.5
Just an alternative method...   After the first hour the distance w 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 w to y, a distance of 45km, Johnny started walking along the same road from y to w. 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?