Two trains are moving in the same direction at the speed of 42 km/hr and 84 km/hr, their lengths are 320 metres and 380 metres respectively. What is the time taken (in seconds) by faster train to cross the slower train?
A work can be completed by 18 boys in 24 days. If 6 boys leave after working for 12 days, then how many days will be needed to complete the remaining work?
Rohit buys a ball for Rs 450 and sells it. Rohit gives two successive discount of 20% and 5% to the customer. What will be the selling price (in Rs) of the ball?