In a group of 75 fourth graders, 20% do not like hot chocolate. how many students like hot chocolate

Let find how many do not like hot chocolate.  

.20*75 = 15 fourth graders don't like hot chocolate. 

Now lets see how many like hot chocolate 

75 -15 = 60 kids like hot chocolate. 

Another way to do this is  you know that 20% of kids don't like hot chocolate then that means 80% must like hot chocolate.  

So now you just have to do .8*75 and you get 60