A survey of $120$ film viewers was conducted to analyze preferences for Horror ($H$), Comedy ($C$), and Drama ($D$):

• $15$ viewers liked all three genres.
• $40$ liked both Horror and Comedy.
• $30$ liked both Comedy and Drama.
• $25$ liked both Horror and Drama.
• The number of viewers who liked only Horror, only Comedy, and only Drama are all equal.
• $10$ viewers liked none of the three. How many viewers in total liked Horror?