Answer:
= 200P - 800
= 400P - 1600
Step-by-step explanation:
let the supply function be : P = MC
P = 4 + Q/20
therefore Q = 20P - 80 ( supply function )
For 10 firms
Q = 10( 20P - 80 ) = 200P - 800
for 20 firms
Q = 20(20P - 80 ) = 400P - 1600
next determine market supply curve under free entry
AC = 4 + Q/40
Hence ; when Q = 0 , AC = 4 and this is for unlimited number of firms