Problems in screenshots

The supply of widgets in a small Michigan city is controlled by 2 producers -- Gratiot and Clinton. The inverse demand for widgets is P = 30 - 2Q and the MC = ATC = $6. Each morning, Gratiot and Clinton make a binding decision about how many widgets to make. Suppose that Gratiot and Clinton agree to collude and evenly split the monopoly output and charging the monopoly price. Suppose that Gratiot cheats on the cartel agreement by producing 1 extra widget each morning. ~ 1. What is the new market price after Gratiot cheats on the agreement and produces an extra widget?