Why do firms enter into a collusive agreement to increase profits?

Carmen’s beauty salon has estimated monthly financing requirements for the next six months as follows: january $ 9,000 april $ 9,000 february 3,000 may 10,000 march 4,000 june 5,000 short-term financing will be utilized for the next six months. projected annual interest rates are: january 9 % april 16 % february 10 may 12 march 13 june 12 what long-term interest rate would represent a break-even point between using short-term financing and long-term financing?