So this type of problem is extremely easy if you just draw it out. RS has a midpoint called M and according to the definition midpoint of line makes both sides of that line to be equal. In this case, midpoint M makes RM and MS equal to each other. Please refer to my work (the picture attached below) to explore how I solved this and feel free to comment for a more in depth explanation.
As kinda like my own thing, since I am a big fan of geomentry, if you have any more from questions, privately message me and I got you. Thanks.