Step-by-step explanation:
63+36+X = 180 (interior angles of a triangle equal 180)
X = 180-99
X= 81
X+Z= 180(angles on a straight line adds up to 180)
81+y= 180
Z=180-81
Z =99
13+Z+Y=180
13+99+Y=180
Y=180-112
Y=68
