1 4. Use x = 5, y = 8 and z = 1 to evaluate z(x + y). x 6 ) A. 6 D. 28 B. 7 C. 14 5. When x = 3 and z = 2, evaluate the expression 6z + 4x. A. 12 B. 21 C. 24 D. 42 6. Find the sum: (19s + 11t) + (14t - 8s) A. 11s + 25t B. 27s + 25t C. 36st D. 33s 7. Find the sum: (2x3 + 3x2 - 5) + (3x2 + 7) A. 2x3 + 6x2 + 2 B, 2x3 + 6x2 12 C. 883 +2 D. 8x2 + 2 8. Subtract and simplify: (7x3 - 5x + 8) - (4x3 - 2x + 1) A. 3x3 + 3x - 7 C. 3x3 3x + B. 3x3 - 7x - 7 D. 3x3 -7x + Find the difference: (2r2 - 6r - 7) - (3r2 - 5r - 8) C. r² - I - 1​