Δ = 1 + 4*20 = 81
x' = (-1 + 9)/2 = 4
x'' = (-1 - 9)/2 = -5
4² + 4 - 20 = 0
(-5)² - 5 - 20 = 0
Ok !
One way you could solve this is to just multiply the top and bottom out so that you get 9/81, reducing it by 9/9 to get 1/9 or option C.
Another way would be to do

since dividing numbers with exponents would be subtracting the bottom exponent from the top exponent, provided that the base number (in this case 3) is the same for both. For this method, you would get

, which is equal to 1/9 or .1 repeating, the same answer that you'd get with the first method.
1) 110+30+a = 180
a = 180-140 = 40
Obtuse angled triangle
2) 50+50+C = 180
C=180-100 =80
Acute angled triangle
3) 45+45+b =180
b =180-90 = 90
Right angled triangle
4) 45+60+C = 180
C = 180-105 =75
Acute angled triangle
5) 94+47+b =180
b = 180-141=39
Obtuse angled triangle
6)81+53+a = 180
a =180-134 = 46
Acute angled triangle
7) 38+45+b =180
b = 180-83 =97
Obtuse angled triangle
8) 36+54+C =180
C =180-90 = 90
Right angled triangle.