Direction : What value should come in place question mark(?) in the following questions?

25 % of 420 - ? % of 140=77

Cost of two articles were in the ratio of 16: 23. The cost of first article increases by 10% and that of second by Rs.477. Now the costs of two articles are in the ratio of 11: 20. The price of the second article (in Rs.) in the beginning was-

A hexagon is inscribed in a circle of radius 14 cm, three of its alternates sides are 22 cm and each and other sides are equal find the length of other three sides?

The average salary of all the staff in an office of a corporate house is Rs 5,000. The average salary of the officers is Rs 14,000 and that of the rest is Rs 4,000. If the total number of staff is 500, the number of officers is

A tap takes 36 hours extra to fill a tank due to leakage equivalent to half of its inflow. The inflow can fill the tank in how many hours?

Two trains of equal length take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 meters, in what time (in seconds) will they cross each other traveling in opposite direction?