The average number of ice cream cones sold in a weekend is 60. On Friday, 67 cones were sold and on Saturday, 59 cones were sold. How many cones were sold on Sunday?

The average would be each number of cones sold per day added, and divided by the number of days (3). So this can be translated into the equation (67 + 59 + x) / 3 = 60/1. Simplified, that is 67 + 59 + x = 180, then 126 + x = 180, then x = 54.

You can check by adding 67 + 59 + 54, which is 180, and divide by 3 days which is 60. So 54 cones were sold on Sunday.