In order to figure this out, we need to find the price per ounce of candy. We can do this by dividing the price of the candy by the amount of ounces of candy that were bought.
Tiffany bought 3 ounces and paid 46 cents, so she bought candy with a rate of 46/3 = 15.33 cents per ounce.
Tony bought 13 ounces of candy and paid 76 cents. He bought candy with a rate of 76/13 = 5.85 cents per ounce.
Because Tony is paying less for each ounce, he made the better buy.