If we have that:
1. The letter x represents the number of children who like ice cream.
2. The letter y represents the number of adults who like ice cream.
Then, we can say that:
1. Case x + y
The addition of the letters, x, and y, x + y, is the total of children and adults who like ice cream.
2. Case x/(x+y)
In this case, we have the number of children with respect to the total of children and adults. Therefore, we have the ratio of the children with respect to the total of children and adults who like ice cream.
In summary, we have that:
The expression x + y represents the total of children and adults who like ice cream.
The expression x/(x+y) represents the ratio of the children with respect to the total of children and adults who like ice cream. We are comparing one part to the total.