Let P be the sum of first n positive terms of an increasing arithmetic progression A. Let Q be the sum of first n positive terms of another increasing arithmetic progression B.

Let P ∶ Q = (5n + 4) ∶ (9n + 6)

What is the value of q if the coefficients of x3 and x6 are equal ?

What is the ratio of the coefficients of middle terms in the expansion (when expanded in ascending powers of x)?

Under what condition the coefficients of x2 and x4 are equal ?