B$6.$ As shown in Fig. B$6,$ three long wires are perpendicular to the page, and each carries a current of $3$ A flowing out of the page. They form an equilateral triangle with sides of $0\mathrm{.}2$ m $.$ A fourth wire $($wire $\backslash ($ b $\backslash ))$ passes through the midpoint of the base of the triangle and is parallel to the other three wires. If the net magnetic force on wire $\backslash ($ a $\backslash )$ is zero, determine the the magnitude and direction $($out of the page or into the page$)$ of the current in wire $\backslash ($ b $\backslash ).$

Fig. B$6$