Respuesta :

3x - 1 = 2x + 9
Subtract 2x from both sides
x - 1 = 9
Add 1 to both sides
x = 10
Plug in
3(10) -1 =29
So 1 and 3 measure 29°
180-29 = 151
So 2 and 4 measure 151°

Hope this helps :)