Answer:
Store C
Step-by-step explanation:
Simply divide the price by the amount to determine which store has the best price efficiency.
A : 12.99 / 100 = .129¢ per oz
B : 9.49 / 70 = .136¢ per oz
C: 10.98 / 90 = .122¢ per oz
Store C has the best price efficiency