We can use the formula for the electric field due to a line of charge:
E = k λ / r
where E is the electric field, k is Coulomb's constant, λ is the charge density, and r is the distance from the wire.
Plugging in the given values:
E = (9 x 10^9 N·m^2/C^2) (142 x 10^-6 C/m) / (0.75 m)
E = 1.90 x 10^3 N/C
Therefore, the magnitude of the electric field 75.0 cm from the axis of the wire is 1.90 x 10^3 N/C.