Respuesta :

the three angles of a triangle always add up to 180 degrees.

So, add the three angles together!

2x - 12 + 2x + 17 + 9x - 7 = 180

Group the similar numbers together.

13x -2 = 180

13x = 182

x = 14

Plug x in to 2x + 17

14*2 + 17 = 45

mX = 45 degrees

Answer:

m∠X = 45°

Step-by-step explanation:

All angles in a triangle add up to 180°

2x - 12 + 2x + 17 + 9x - 7 = 180

13x = 180 - 17 + 12 + 7

13x = 182

x = 14°

m∠X = 2x + 17

sub x = 14° into m∠X

2(14) + 17

m∠X = 45°