The force generated by a magnetic field B perpendicular to a wire carrying a current I is
[tex]F=ILB[/tex]
where L is the length of the wire.
If we divide both sides for L, we get
[tex] \frac{F}{L}=IB [/tex]
where the ratio on the left is the force per meter of length, which is exactly what we want to find. So:
[tex] \frac{F}{L}=IB=(9.75 A)(0.81 A)=7.90 N/m [/tex]
