Answer:
B=1.04*10^{-4}T
Step-by-step explanation:
An infinite wire produces a magnetic field that can be computed with the formula:

where m0 is the magnetic permeability of vacuum (4pi*10^{-7}Tm/A), I is the current of the wire (2.50A) and r is the perpendicular distance to the wire in which B is calculated (3cm=3*10^{-2}m). By replacing we obtain:

hope this helps!!