First let us find out which supplier gives the lower price
For first supplier we have:-
![\begin{gathered} 5\operatorname{kg}=12.75 \\ 1\operatorname{kg}=(12.75)/(5) \\ =2.55 \end{gathered}]()
So rate of first supplier is 2.55/kg
Now for second supplier we have :-
![\begin{gathered} 7\operatorname{kg}=18.34 \\ 1\text{ kg=}(18.34)/(7) \\ =2.62 \end{gathered}]()
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:-

So Jeff needs to pay 58.65$ if he buys 23 kg o