Hi! To be able to solve questions such as these, you only have to divide the price by its quantity.
1) Brand A: $13.98 for 177 fl oz
[tex]\frac{13.98}{177} [/tex] = $0.08 per fl oz
2) Brand B: $19.98 for 225 fl oz
[tex]\frac{19.98}{225} [/tex] = $0.09 per fl oz
Davis should select Brand A since it's cheaper per fl oz.