What will be the constant term in the expansion of (x + 1/x)^6?

If x^3 – y^3 = 117/8 and x – y = 3/2 then the value of x^2 + xy + y^2 will be

A father is five times as old as his son, but after 15 years, he will remain only twice as old as his son. What is the age of the father?

What is the largest power of 10 that divides the product 29×28×27 x...2×1?

If a, b, c, d, e and f satisfy 2a = 3b = 6c = 9d = 12e = 18f, then what is the value of (a + b)/(c + d + e + f)?

In a row of boys, A is 15th from the left and B is fourth from the right. There are three boys between A and B, C is first left of A. What is the position of C from the right?