Step-by-step explanation:
middle angle is 90° as shown in figure.
(8k+1)°+90°+49°=180°(by straight angle )
8k+1+90+49=180°
8k+91+49=180°
8k+140=180°
8k+=180°+140°
8k=40°
k=40°/8
k=5
(8k+1)°=8×5+1=41°
