C can complete a work in 20 days. If C works for 5 days and then D finishes the remaining work in 10 days, how long would D take to complete the entire work alone?
Five friends P, Q, R, S, and T are sitting in a row. P is to the left of Q, but not next to R. S is sitting next to R. T is sitting at one of the ends. Who is sitting in the middle?