In the initial Cournot duopoly equilibrium, both firms have constant marginal costs, m, and no fixed costs,

Question:

In the initial Cournot duopoly equilibrium, both firms have constant marginal costs, m, and no fixed costs, and there is a barrier to entry. Show what happens to the best-response function of firms if both firms now face a fixed cost of F.
Let market demand be
P = a-bQ,
where a and b are positive parameters with 2 firms.
Let q1 and q2 be the amount produced by firm 1 and firm 2, respectively. Assuming it is optimal for the firm one to produce, its best-response function is
q1=???.