Respuesta :

8x+3 + 5x+15 + 7x+2 = 180
20x + 20 = 180 
20x = 180 - 20
20x = 160
x = 160/20
x = 8

∠С = 5x+15 = 5*8 + 15 = 55°
5x + 15 + 8x + 3 + 7x + 2 = 180
20x + 20 = 180
-20 -20
20x = 160
/20 /20
x = 8
5x + 15
5(8) + 15
40 + 15 = 55 <---- measure of angle C