(a) the magnitude of force per unit length= 3.46 x 10⁻⁵ N/m
(b) The force is repulsive.
Step-by-step explanation:
(a) The force per unit length between two conductors is given by

i1= current in the first wire= 1.7 A
i2= current in the second wire = 3 A
r= distance between the wires= 2.95 cm=0.0295 m
= 10⁻⁷ Tm/A
so F= (10⁻⁷) (2 * 1.7 * 3 )/(0.0295)
F= 3.46 x 10⁻⁵ N/m
(b) since the wires are carrying the currents in the opposite directions, so the force between them is repulsive.