If pq+qr+rp=0 then find the value of $$ {p^{2}\over {p^{2}-qr}}+{q^{2}\over {q^{2}-rp}}+{r^{2}\over {r^{2}-pq}}$$

A can write 75 pages in 25 hrs. A and B together can write 135 pages in 27 hrs. In what time can B write 42 pages?

Running 4/3 of his usual speed, a person improves his timing by 10 minutes. Find his usual time to cover the given distance.

A train travelling at 48 km/hr crosses an another train half of its length and travelling in opposite direction at 42 km/hr in 12 seconds. It also passes a railway platform in 45 seconds. The length of the railway platform Is

A pipe can fill a tank in x hours and an another can empty it in y hours. In how many hours will they together fill it. If y>x?

By selling 66 metres cloth, a man loses S.P. of 11 metres. What is the loss percent?

A borrowed Rs.1500 at 4% per annum and Rs.1400 at 5% per annum for the same period. He paid Rs.390 as total interest. Find the time for which he borrowed the sum.

A train passes two bridges of length 400 m and 200 m. in 50 seconds and 30 seconds respectively. The length of the train is-