**Classifying & Simplifying Polynomials: Degree and Number of Terms**

1. Simplify the expression:
\[ 8x - 2 + x^2 - 20x + 5 \]
Combine like terms:
\[ (8x - 20x) + (-2 + 5) = x^2 - 12x + 3 \]

2. Simplify the expression:
\[ 5x^2 - 4x^3 - 8x + x^2 \]
Combine like terms:
\[ (-4x^3) + (5x^2 + x^2) - 8x = -4x^3 + 6x^2 - 8x \]

3. Simplify the expression:
\[ x^6 - 24 - 5x^5 + 13 \]
Combine like terms:
\[ x^6 - 5x^5 + (-24 + 13) = x^6 - 5x^5 - 11 \]

5. Simplify the expression:
\[ 26x^4 - 9 + 3x - 17x^2 \]
Combine like terms:
\[ 26x^4 - 17x^2 + 3x - 9 \]

6. Simplify the expression:
\[ 713x^3 - 9x + 27x^3 \]
Combine like terms:
\[ (713x^3 + 27x^3) = 740x^3 \]
\[ 740x^3 - 9x \]

8. Simplify the expression:
\[ 4x - 18 - 5x + 17 \]
Combine like terms:
\[ (4x - 5x) + (-18 + 17) = -x - 1 \]

9. Simplify the expression:
\[ 39x^3 + 18x - 1 + 5x^4 - x^2 \]

10. Simplify the expression:
\[ -45 - \frac{1}{8}x + 30 + 10x + 15 \]
Combine like terms:
\[ (10x - \frac{1}{8}x) + (-45 + 30 + 15) = \frac{79}{8}x + 0 \]

11. Simplify the expression:
\[ -x - 13 + 3x - 2x + 11x^2 \]
Combine like terms:
\[ 11x^2 + (-x + 3x - 2x) - 13 = 11x^2 - 13 \]

12. Simplify the expression:
\[ 7x - 19 - 6x - 24 + 13x^2 \]
Combine like terms:
\[ 7x - 6x = x \]
\[ -19 - 24 = -43 \]
\[ 13x^2 + x - 43 \]

**Note**: There was a repeated "Simplify the expression" for numbers 9 and 12, but with different expressions. Ensure to verify and separate tasks if needed.