One hour after Matthew started waking from q to y, a distance of 45km, Johnny started walking along the same road from y to q. 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? Select the correct option:  A) 24  B) 23  C) 22  D) 21  E) 19.5

Rationale: just an alternative method . . . after the first hour the distance q 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 a .
Answer: A