A motorboat, whose speed is 45 km./hr. in still water goes 180 km. downstream and comes back in a total of 9 hours. The speed of the stream (in km/hr.) is-

If there is a reduction in the number of workers in a factory in the ratio 65 : 17 and an increment in their wages in the ratio 34 : 125, then the ratio by which the total wages of the workers should be decreased is-

A man left 9 minutes early than the scheduled time and in order to reach the destination 378 km away in time, it has to slow its speed by 6 km/h from the usual. What is the usual speed (in km/hr.) of the man?

Three bottles of equal capacity are containing a mixture of milk and water in ratio 1: 3, 3: 5 and 11: 5 respectively. These three bottles are emptied into a large bottle. What is the ratio of milk and water respectively in this large bottle?

Two trains are moving in the same direction at speed of 54 km/h and 92 km/h, their lengths are 400 m and 360 m respectively. What is the time taken (in seconds) by faster train to cross the slower train?

Find the exact value of the following question:

$$ \sqrt {123×8+2389-1164}=? $$

Find the exact value of the following question:

$$ (13+2\sqrt{5})^2=?\sqrt{5}+189 $$

Find the exact value of the following question:

$$ 8\sqrt{?}÷14×3+9=21$$