A completes a work in 15 days, B completes the same work in 8 days while B and C jointly complete the same work in 4 days. If A and C jointly complete the same work in x days while A and B jointly complete it in y days, what is the value of x/y (A) 1 (B) 1/2 (C) 1 1/2 (D) More than one of the above (E) None of the above