Respuesta :

the interior angles of a triangle add up to be 180 degrees

which means
10x-4+8x+3+91=180

can you solve for x?
91+18x−4+3=180
18x+90=180
18x=180−90
18x=90
x= 
[tex] \frac{90}{8} [/tex]

x=5
Hope this helped!