P, Q and R together can do a piece of work in 56 days. P and Q together can do one-fourth as much work as R alone. In how many days can P and Q together complete the entire work?
A pole stands vertically inside a scalene triangular park ABC. If the angle of elevation of the top of the pole from each corner of the park is same, then in ΔABC, the foot of the pole is at the
A, B and C can complete a certain work in 30 days. B and C together can complete the same work in 45 days. If B is 20% more efficient than A, then B alone can complete one-third of the same work in: