Answer:
3420°
Step-by-step explanation:
The sum of angle measures of an n-gon is ...
angle total = (n-2)×180°
For n = 21, the angle total is ...
21-gon total = (21 -2)×180° = 3420°
+the answer is $340 to find the answer you need to take $600 and since its twice the cost plus $40 you divide $600 by 2 then you add $40 $600/2 +$40=$340
