Question

please give answer of this question.

Answer 1

2a+2b=180 (since its a straight line)
=>2(a+b)=180
=>a+b=90

Answer 2

in the given figure a = 20°

from the figure
a + a + b + b = 180°
2a + 2b = 180°
2(20°) + 2b = 180°
40° + 2b = 180°
2b = 180-40 = 140°
b = 70°

and
a + b = 70 + 20 = 90°