I think the only way you can solve this is to assume that <R means PRT in the given ratio. If I am wrong, I don't think the problem can be solved.
Find <T
Let <T = x
and <PRT = 3x
KLMN is a Parallelagram and therefore two adjacent angles are supplementary.
<PRT + <T = 180 degress
3x + x = 180 degrees
4x = 180
x = 45
So <T = 45
<PRT = 3*45 = 135
If RD is perpendicular to PS then <PDR = 90o
Here's the trick.
RD is also Perpendicular to RT
<MRD + <MRT = 90
<MRT = 180 - 90 - <T
<MRT = 180 - 90 - 45
<MRT = 45
Here comes your answer
=================
<MRD + MRT = 90
<MRD + 45 = 90
<MRD = 45
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Note: you must ignore everything to do with the diagram. It is not drawn to scale and the letters are not the same as in the question. The only thing you use is that the figure is a ||gm
