Consider a market with an inverse demand function, P $($Q$)=605$Q$.$ There are

two possible suppliers in the market, firms A and B$.$ They are engaged in Cournot

competition with each other $($simultaneous quantity competition$).$ Denote by QA and

QB $,$ the quantity choices of firms A and B$,$ respectively. Total supply to the market is

Q $=$ QA $+$ QB $.$ Firm A has a cost function CA$($Q$)=10$Q and firm B has cost function

CB $($Q$)=20$Q$.$

$($a$)$ Determine Firm A$$s best response function, $$QA $($QB $),$ to any quantity choice by

firm B$,$ QB $0.$ By similar argument determine B$$s best response function,

$$QB $($QA$)$