Answer:
x=5
Step-by-step explanation:
The sum of the angles of a triangle equal 180 degrees
91+ 8x+3 + 10x-4 = 180
Combine like terms
90 +18x = 180
Subtract 90 from each side
90-90+18x = 180-90
18x = 90
Divide by 18
18x/18 = 90/18
x =5
