An amount of money is to be distributed among P, Q and R

An amount of money is to be distributed among P, Q and R in the ratio of 2 : 7 : 9. The total of P’s and Q’s share is equal to R’s share. What is the difference between the shares of P and Q ?

Let the amount to be distributed be ₹ x.
P : Q : R = 2 : 7 : 9
Sum of the ratios = 2+7 + 9 = 18

∴ P =	2	× x =	x
	18		9

Q =	7	x
	18

R =	9x	=	x
	18		2

As given,

x	+	7x	=	x
9	+	18	=	2

Thus, we get no conclusion.
Amount should necessarily be known.