Part A

There are three long, straight, parallel wires depicted, all lying in one plane and carrying current in an upward direction. Find the force exerted on a $30-$ cm segment of wire B if $I=20A,r_1=2\mathrm{.}0cm,$ and $r_2=2\mathrm{.}0cm.$

Express your answer with the appropriate units. Enter a positive value if the force is rightward and a negative value if the force is leftward.