If this was you image:
Ice tea: 30%
Lemonade: 32%
Colas: ?
The percent of the drinks sold that were colas is 38%.
One whole circle is equivalent to 100%. Since the ice tea takes up 30% of the circle and lemonade takes up 32% of the circle, the remaining portion for colas is no longer 100%. We simply deduct these percentages from 100% to get the percentage of colas which is 38%.
