(3y^2-5x^2+4)-(2x-8+4y^2)
Distributing the negative across the terms in the second set of parethesis, we have:
3y^2 - 5x^2 + 4 - 2x + 8 - 4y^2 Combine like terms
3y^2 - 4y^2 - 5x^2 - 2x + 4 + 8 =
- y^2 - 5x^2 - 2x + 12
