I think for X you do: [tex]180 = 90 + 2x + x[/tex] then subtract the 90 to 180 and add the Xs together [tex]90 = 3x[/tex] then divide 90/3 to get X [tex] \frac{90}{3} = 30[/tex] to check put 30 in for X to make sure it = 180
Now for Y and Z I'm not sure what to do, I hope this helped a little
