You need isolate the object draw just a simple box to represent it and you need to identify the kind of plane the object is acting on an incline plane so you will need to resolve the gravity to parallel and perpendicular components then think if the object is static so some forces on the x axis = 0 and also the sum on the y would = 0 .

You could let u = sinx so it's just u²-u-1=0 do you solve it using the general formula or the calculator to get (2u+1)(u-1) so you get u = 1 and u=-1/2 and we said u = sinx so x = sin inverse of 1 and -1/2 to get 90 , 210