find the missing value

We can set up the equation to find the missing value as follows:

(?) * (7y^5 - 3y) = 35y^14 - 15y^10

To solve for the missing value, we can divide both sides of the equation by (7y^5 - 3y):

? = (35y^14 - 15y^10) / (7y^5 - 3y)

Simplifying the right side of the equation gives us:

? = 5y^10(7y^4 - 3)

Therefore, the missing value is 5y^10(7y^4 - 3).