Please help im finding this very difficult

First calculate price per gram (J) of both jars.
Large jar: [tex]J_L=\dfrac{440\mathrm{g}}{1.54\mathrm{£}}\approx 285.71 \mathrm{\frac{g}{£}}[/tex]
Small jar: [tex]J_S=\dfrac{340\mathrm{g}}{1.26\mathrm{£}}\approx 269.84\mathrm{\frac{g}{£}}[/tex]
Because [tex]J_S < J_L[/tex] we can conclude [tex]J_S[/tex] has best value.
Hope this helps.