Answer:
a=12
Step-by-step explanation:
a/40=3/10
10 x 4=40, so
3 x 4=12
n = 20.
The external angles of a polygon add up to 360 degrees. So:
30 + 42 + 16(n - 2) = 360 where n is the number of sides of the polygon.
16n + 30 + 42 - 32 = 360
16n + 40 = 360
16n = 320
