At a breakfast buffet, 45% of people choose coffee for their beverage while 25% choose juice. also, 15% choose both coffee and juice. what percentage of people prefer neither coffee or juice?

First of all, 100% is the total
to find out the percentage of people who prefer neither coffee or juice

45 + 25 + 15
That is 85 out of 100 prefer certain drinks
to calculate those that prefer neither coffee or juice
100-85 
15
15% percent prefer neither coffee or juice

Hope this helps :)