Let x represent one case of conductor ties
If one case of conductor ties weighs 22.15 pounds, i.e
[tex]x=22.15\text{pounds}[/tex]For 3 1/2 cases of ties i.e
[tex]3\frac{1}{2}\times x=\frac{7}{2}\times x=\frac{7x}{2}[/tex]The weight of will be,
[tex]\frac{7x}{2}=\frac{7\times22.15}{2}=\frac{155.05}{2}=77.525\text{pounds}[/tex]Hence, it weighs 77.525pounds