First let us find out which supplier gives the lower price
For first supplier we have:-
[tex]\begin{gathered} 5\operatorname{kg}=12.75 \\ 1\operatorname{kg}=\frac{12.75}{5} \\ =2.55 \end{gathered}[/tex]So rate of first supplier is 2.55/kg
Now for second supplier we have :-
[tex]\begin{gathered} 7\operatorname{kg}=18.34 \\ 1\text{ kg=}\frac{18.34}{7} \\ =2.62 \end{gathered}[/tex]So rate of second supplier is 2.66/kg
So first supplier gives the lower price.
Now the money that Jeff need to pay will be:-
[tex]\begin{gathered} 23\times2.55 \\ =58.65 \end{gathered}[/tex]So Jeff needs to pay 58.65$ if he buys 23 kg o