Geometry, is this right if not whats the answer ?

Explanation:

Because S and T are midpoints of segments PQ and QR, we know that ST is a midsegment of triangle PQR. Consequently, this means ST is parallel to PR.

From the same side interior angle theorem, the angles (11x-3) and (5x-9) are supplementary angles. This is only true because of the parallel lines.

So we can say the following:

(angle P) + (angle S) = 180

(5x-9) + (11x-3) = 180

(5x+11x) + (-9-3) = 180

16x - 12 = 180

16x = 180+12

16x = 192

x = 192/16

x = 12

Use this to find angle PST

angle PST = 11x-3

angle PST = 11*12-3

angle PST = 132-3

angle PST = 129 degrees

Optionally we can find angle QPR

angle QPR = 5x-9

angle QPR = 5*12-9

angle QPR = 60-9

angle QPR = 51 degrees

As a check, adding the two angles we found should get us 180

(angle PST)+(angle QPR) = 129+51 = 180

The answer checks out.