Task: Question Answering
Input (English): Question: One hour after Matthew started waking from e to y, a distance of 45km, Johnny started walking along the same road from y to e. 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?

 Option A: 24

 Option B: 23

 Option C: 22

 Option D: 21

 Option E: 19.5
Output (English): Option A