Arithmetic Reasoning - General Questions

In a farm there are hens and cows. If the heads number 37 and the legs number 128, how many hens are there?

In a farm there are hens and cows. If the heads number 57 and the legs number 150, how many hens are there?

A boy buys 4 notebooks at Rs. 11 each and pays with Rs. 100. How much change does he get?

28 poles are fixed in a straight line, 6 m apart. What is the distance between the first and the last pole?

17 poles are fixed in a straight line, 5 m apart. What is the distance between the first and the last pole?