The figure shows four penguins that are being playfully pulled along very slippery (frictionless) ice by a curator. The masses of three penguins and the tension in two of the cords are m_1=12 kg, m_3=15 kg, m_4=20 kg, T_2=111 N, and T_4=222 N. Find the penguin mass m_2 that is not given