Hi, srirahulan. My physics is a little rusty, but if I remember correctly this is more or less a trig problem. I have attached a picture that should get you started. A few other things that may be helpful:
1. You know what the green vector is from the given information.
2. The answer to part a) is the red part of the triangle (expressedin Newtons) in the picture.
3. To solve part b) take all the forces that are going "down the ramp" and subtract them from any forces that are known to be pushing "up the ramp"
4. The answer to part c) is the blue part of the triangle (expressed in Newtons) in the picture.