>>11534020If I2 is greater than I1, then I3 can go in that direction. As others said, when solving you can ignore the direction of the arrow. you will just get a negative value if the arrow is pointing the wrong way, which is perfectly fine. when you pick currents for your equations you should not worry about directions. If I2 > I1 however, you will get a positive value for I3=I2-I1, indicating that all the arrows are pointing in the real current directions in that case.
