Answer
4.4 A in the same direction as the first current.
Work Step by Step
If the currents are in the same direction, then the 2 magnetic fields, halfway between the currents, will point in opposite directions. Their magnitudes are subtracted, and the net field can be zero.
$$B_{net}=0=\frac{\mu_oI_1}{2\pi r_1}-\frac{\mu_oI_2}{2\pi r_2}$$
$$I_2=I_1\frac{r_2}{r_1}$$
$$I_2=(2.0A)\frac{4.8cm}{2.2cm}=4.4A$$
