Adam who is 20 years old is 4 times as old as Mary. What will be Mary’s age when Adam is twice as old as her?

What should be the missing term in the following number series?
61, 67, 71, 73, 79, 83, __, 97,

A is father of B and C. B is the son of A. but c is not the son of A. How is Created to A? 

Subash travelled 15 km. towards East, then turned towards North and travelled 15 km and turned towards West and travelled 15 km. How far is he from the starting point? 

If L=+, M= - , N = ×, P=÷ then 5 N 5 P 5 L 5 M 5 =?

64 : ? :: 72 : 53

Coal : Heat : : Wax : ? 

In a line 13 persons are sitting. A is seventh from the beginning and two persons 15. sits between G and A. Persons between A and L is same as persons between G and Q, Then what is the position of Q from the beginning?