Respuesta :

4y-6+7y+21 = 11y+15 = 180
11y = 165
y=15

Hope this helps!! :)
4y - 6 +7y +21 = 180
11y + 15 = 180
11y = 180 -15
11y = 165
y = 15

<ABC = 7y +21
= 7(15) + 21
= 105 + 21
= 126