Answer:
24 calories
Explanation:
When calculating with percentages, you need to first convert your percentage to a decimal by dividing by 100:
40/100 = 0.40
Since you want to know the amount of calories in a piece of sugar-free gum that is 40% less calories than regular gum, what you really want to know is the total amount of calories that 60% of the regular gum would produce.
1 - 0.40 = 0.60
0.60 x 40 = 24 calories
To check your answer, you can multiple 40 x 0.40 = 16 and subtract 16 from 40: 40 - 16 = 24.