The two teams include a total of 25 + 19 = 44 players.
There are exactly 36 students who are at least one team.
Thus, there are 44 − 36 = 8 students who are counted twice.
Therefore, there are 8 students who play both baseball and hockey.
⇒ Solution 2
Suppose that there are x students who play both baseball and hockey.
Since there are 25 students who play baseball, then 25−x of these play baseball and not hockey.
Since there are 19 students who play hockey, then 19−x of these play hockey and not baseball.
Since 36 students play either baseball or hockey or both, then
→ (25 − x) + (19 − x) + x = 36
(The left side is the sum of the numbers of those who play baseball and not hockey, those who
play hockey and not baseball, and those who play both.)
Therefore, 44 − x = 36 and so x = 44 − 36 = 8.
Thus, 8 students play both baseball and hockey.