y I=4 A

A long straight wire carrying a 4-A current is placed along the x-axis as shown in the figure. A proton is traveling in the vicinity of this wire. 
(a) At the instant the proton is at point P, 4.50 cm above the wire’s center and moving with a speed of 6×10⁴ m/s directly toward it, what is the force (magnitude and direction) that the magnetic field of the current exerts on the proton?
(b)  explain how you've determined the direction of the force in part (a).
(c) What would be the magnetic force (magnitude and direction) if the proton were instead moving parallel to the wire in the same direction as the current?
(d)  explain how you've determined the direction of the force in part (c).

μ₀ = 4π × 10^-7 T ∙ m/A
e = 1.6 × 10^-19 C