A psychiatrist has 4 patients that need 25 sessions in total. One of the patients needs 6 sessions. Another patient needs 5 more than that. How many sessions would the remaining patients need?
The second patient needs 6+5 = <T>add(6, 5)=11 sessions.
The first two patients need 6+11=<T>add(6, 11)=17 sessions total.
25-17=<T>subtract(25, 17)=8 sessions.
