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?

The following equation is incorrect. Which two signs should be interchanged to correct the equation?
12 + 10 - 28 ÷ 7 x 4 = 48

If P means -, Q means +, R means x and  S means ÷ then what is the value of  8 R6S3Q5P9 

If F = 6 and FOX = 45, then find the value of LION.

The total age of a mother and her son is 60 years. The difference between their ages is 30 years. Find out the age of the mother.

If -4$1 = 4, 7$-7 = 49 and 3$1 = -3, then find the value of -8$-5 = ?

The average age of father and his son is 22 years. The ratio of their ages is 10 : 1 respectively. What is the age of the son?

Which of the following least number can be subtracted from 2486 to make it a perfect square?