If the line bisects it then it cuts directly down the center, meaning both sides will be equal.
so since we know RAY and YAS and we know they are equal, we can use that to find x
8x-4=5x+20
add the 4 over and subtract the 5 over
3x=24
divide
x=8
now put that into both equations
8(8)-4= 60
5(8)+20=60
the line RAS is 120 degrees