7y + 3y = 180
10y = 180
y = 180/10
y = 18
so < 9 = 7y = 7(18) = 126
< 10 = 3y = 3(18) = 54
< 9 and < 11 are corresponding angles....so they are equal....so < 11 is 126 degrees....< 11 and < 16 are vertical angles...so they are equal....so < 16 is 126 degrees <==
