This question is from jeff sackmann's 1000 problem set, which is superb. I know I can solve this by plugging in numbers, and that's actually the explanation that jeff gives. But I want to know how to do it algebraically. I tried figuring it out but couldn't get to the right answer.
Hayden began walking from F to G, a distance of 40 miles, at the
same time Ava began walking from G to F on the same road. If
Hayden’'s walking speed was x miles per hour and Ava’'s was y
miles per hour, how many miles away from F were they, in terms
of x and y, when they met?
(A) 40(x-y)/x+y
(B) 40x-y/x+y
(C) x-y/x+y
(D) 40y/x+y
(E) 40x/x+y
Hayden began walking from F to G, a distance of 40 miles, at the
same time Ava began walking from G to F on the same road. If
Hayden’'s walking speed was x miles per hour and Ava’'s was y
miles per hour, how many miles away from F were they, in terms
of x and y, when they met?
(A) 40(x-y)/x+y
(B) 40x-y/x+y
(C) x-y/x+y
(D) 40y/x+y
(E) 40x/x+y
