Respuesta :

2x + 90 + x + 60 - x = 180
2x + 150 = 180
2x = 180 - 150
2x = 30
x = 15

check..
2x = 2(15) = 30
90
15
60 - 15 = 45

30 + 90 + 15 + 45 = 180
180 = 180 (correct)