Thoughts on the solution:

Let x = angle PQR
Let y = angle PRS

Question is how much more is PRS than PQR, or what is :
y - x equal to

As the sum of the angles will be 180 both statements allow us to deduce that angles PQR plus QRP equal 150. So they are either both right from a standalone perspective or neither is sufficient.

Can we use this info to solve it

x + (180 - y) = 150
x - y = -30
multiplying across by -1 we get
y - x = 30

So we can solve it with either bit of data and the answer is D

thanks!