In the circuit shown below, R1 = 3 k ohm, R2 = 6 k ohm, R3 = 5 kohm, R4 = 8 kohm, R5 = 9 k ohm, R6 = 4 kohm, R7 = 9 k ohm, V1 = 9 v, V2 = 6 v, and IS = 9 mA. Using superposition, find the current i0 shown, in units of mA, approximated to 2 decimal places.