Respuesta :

This is called Triangle Angle Sun theorem.

Add all the numbers in the triangle.
3x+5+2x+18+2x+17=180

From here you should add up all the variables and numbers.

7x+40=180

Subtract 40 from both sides

7x=140

Divide

X=20

To find the measure angles of each:

Plug in 20 in the x.

3(20)+5=65
2(20)+18=58
2(20)+17=57

Add up all the final numbers and it comes down to 180!