First, it's worth noting that angles on a straight line sum to 180°. We can use this information to find out the value of y: 180-52-59=69 y=69° Another rule is that the angles in a triangle sum to 180° as well. This means that we can now find out x: 63+y+x=180 63+69+x=180 180-63-69=x x=48°