4 of the samples are pure compounds and the other is a mixture. Which two samples are of the same compound?

In T, weight ratio A : B = 7 : 12.5 = 1 : 1.79
In V, weight ratio A : B = 28 : 25.0 = 1 : 0.893
In W, weight ratio A : B = 25 : 14.0 = 1 : 0.56
In R, weight ratio A : B = 14 : 37.5 = 1 : 2.68
In S, weight ratio A : B = 14 : 25.0 = 1 : 1.79

As T and S contain the same weight ratio of A to B, they are the two samples of the same compound.

The answer: (d) T and S

There seems to be something you aren't telling us here. What do weight A and weight of B represent? T and S have a difference in the same proportions so I would guess they are the same material.