Going to need a bit more information than that.
1. Notice that RT is twice the length of RS (i.e. RT = 2RS). You know angle RST is a right angle as RT is your diameter so using your trigonmetric functions, we see that :
2. If two chords, call them AB and CD, intersect at some point P in the circle, then (PA)(PB) = (PC)(PD). Applying that to your question, (QM)(QP) = (QL)(QM). Solve for x.