Posted by Catherine on Tuesday, June 25, 2013 at 3:05pm.
Alec, Kate and Ketan are roommates who share living expenses in a ratio of
k: 2a: 5k
respectively. If their total expenses each month equal $1400, how much is Ketan's monthly contribution?
(A) 280/2a+6k
(B) 700/2a+6k
(C) 1400k/2a+6k
(D) 2800a/2a+6k
(E) 7000k/2a+6x
Please help! I have no idea how to do this.

Math  Steve, Tuesday, June 25, 2013 at 3:35pm
k+2a+5k = 1400
6k+2a = 1400
1400/(2a+6k) = 1
multiplying by 5k, we get
7000k/(2a+6k) = 5k
So, (E)
To check, plug in something simple like k=100 and see what you get.