(x³ - 5x² + 7)+ (3x² + 5x - 2)+ (2x³ - x + 7) is equal to:

1. 3x³ - 2x² + 4x + 12

2. 3x³ + 2x² - 4x + 12

3. 3x³ - 2x² - 4x - 12

4. 3x³ + 2x² + 4x + 12

(x³ - 5x² + 3x + 2) - (6x² - 4x³ + 3x + 5) is equal to:

1. 5x³ + 11x² - 2

2. 5x³ - 11x² + 3

3. 5x³ - 11x² - 3

4. 5x³ + 11x² + 3

(ab - bc) - (ca - bc) + (ca - ab) is:

1. bc - ab

2. ab - ca

3. 2(ab - bc - ca)

4. 0

Separate the constants and variables from the following:

- 7, 7 + x, 7x + yz, $\sqrt{5}$, $\sqrt{xy}$, $\dfrac{3yz}{8}$, 4.5y - 3x, 8 - 5, 8 - 5x, 8x - 5y x p and 3y²z ÷ 4x