Final answer:
The number of dance trend videos is 12.
Step-by-step explanation:
To find the number of dance trend videos, we first need to find the total number of other videos. Since the ratio of dance trend videos to other videos is given as 2:5, we can set up the equation 2x + 5x = 42, where x represents the common ratio. Solving this equation, we get x = 6. Therefore, the number of dance trend videos is 2x = 2 * 6 = 12.