In a survey of students about favorite​ sports, the results include 34 who like​ tennis, 37 who like​ football, 17 who like tennis and​ football, 21 who like tennis and​ baseball, 25 who like football and​ baseball, 9 who like all three​ sports, and 7 who like none of the sports. How many students like only tennis and​ football?

please help me on this ;-;