Solve:

(a) 6x + (9x − 2x)

(b) 11y + 2y + 3x

(c) 11z + 3z + z

(d) 8ab + (−3ab)

(e) 3x − 4x + 7x

(f) 35b − (16b + 9b)

(g) (9a − 3a) + 4a

Multiply:

(a) 5 × b

(b) x × y

(c) 2a × 3b

(d) a × a

(e) 6a × 2a

Find the value of:

(i) 3x + 2y when x = 3 and y = 2

(ii) 5x - 3y when x = 2 and y = 5

(iii) a + 2b - 5c when a = 2, b = 3 and c = 1

(iv) 2p + 3q + 4r + pqr when p = 1, q = 2 and r = 3

(v) 3ab + 4bc - 5ca when a = 4, b = 5 and c = 2

Find the value of:

(i) 2x² - 3x + 4 when x = 2

(ii) 4x³ - 5x² - 6x + 7 when x = 3

(iii) 3x³ + 9x² - x + 8 when x = 4

(iv) 2x⁴ - 5x³ + 7x - 3 when x = 2