Add the following expressions:

(i) 2x², -5x², -x², 6x²

(ii) x² - 2xy + 3y², 5y² + 3xy - 6x²

(iii) 2x + 9y - 7z, 3y + z - 3x, 2z - 4y - x

(iv) 2ab + 3bc - 5ca, 4bc - 3ab + 7ca, 2ca - ab - 5bc

(v) 3x³ + 2x² - 6x + 3, 2x³ - 3x² - x - 4, 1 + 2x - 3x² - 4x³

(vi) 3n² + 5mn - 6m², 2m² - 3mn - 4n², 2mn - 3m² - 7n²

(vii) 3z³ - z² + 5, 1 - 2z + z², 3 + 2z - z³

Simplify:

(i) 5x + 3y - 8z + 2y - 3x + 5z + z - 7y - 2x

(ii) 4x³ - 2x² + 5x - 1 + 8x + x² - 6x³ + 7 - 6x + 3 - 3x² - x³

(iii) 2x² + 3xy - 3y² + x² - xy + y²

(iv) 2 - 3z² + 5yz + 7y² - 8 + z² - 6yz - 9y² + 1 - 2z² - 2yz - y²

(v) 2m - 3n + 5p + 2m + n - 2p - 3m - 4n + p

Find the perimeter of a triangle whose sides are 2y + 3z, z - y, 4y - 2z.

Subtract:

(i) 3a - 2b + 4c from 5a - 3b - 5c

(ii) 5x² - 3xy - 7y² from 3x² - xy - 2y²

(iii) 3p³ - 5p²q + 2q² from q² + p²q - 4p³

(iv) ab - bc - ca from 3ab + 2bc - 4ca

(v) 3z³ - 2z² + 7z - 8 from 8 - z - z²

(vi) 2abc - a² - b² from b² + a² - 2abc