Given:
Number of people bought tickets for comedy = 
Number of people bought tickets for horror = 
Number of people bought tickets for kids movie = 
To find the number of people who bought tickets for the action movie.
Let us take,
Total number of tickets = 1
Now,
Total number of tickets for comedy, horror and kids movie are = 
So,

LCM of 5,4,10 = 20
= 
= 
Rest are action movie's tickets.
Therefore,
Number of action movie tickets = 
= 
= 
Hence,
The number of people who bought the tickets for action movie is
.