For the circuit to the below, consisting of three ideal batteries and three ideal resistors, calculate the current through point P. Let the sign of the current correspond to its direction, with "up" being positive.
E1 = 28.0 V, E2 = 15.0 V, E3 = 27.0 V
R1 = 2.70 kΩ, R2 = 21.0 kΩ, R3 = 9.50 kΩ