Suppose Ariel and Prince Eric are getting married, and their parents, King Triton and Grimsby, are paying for the wedding. The men's individual demand curves for fireworks are given by:
Grimsby: P = 180 - 3Q
Triton: P = 300 - 5Q
Fireworks cost $40.
Ariel's friend Flounder would also like to contribute to the fireworks. If Flounder helps pay for fireworks, the socially optimal quantity will increase by 1.

What is the equation of Flounder's demand curve?