Current Attempt in Progress

In the figure, four long straight wires are perpendicular to the page, and their cross sections form a square of edge length $a=17\mathrm{.}5cm.$ Each wire carries $4\mathrm{.}00$ A$,$ and the currents are out of the page in wires $1$ and $4$ and into the page in wires $2$ and $3.$ In unitvector notation, what is the net magnetic force per meter of wire length on wire $4?$

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widehat$(j)$ Units