Add the following polynomials: (12y2 + 17y - 4) + (9y2 - 13y + 3)
Add the following polynomials: (2x3 + 7x2 + x) + (2x2 - 4x - 12)
Subtract the following polynomials: (3a2 + 2a - 2) - (a2 - 3a + 7)
Subtract the following polynomials: (5x2 - 2x - 1) - (3x2 - 5x + 7)