Here is a breakdown of the simplifications for each expression in the provided worksheet. I will combine like terms step by step.

Simplifications:

1. 7. $7k + 9k$:
   Combine the terms:
   $7k + 9k = 16k$.

2. 8. $-9p + p$:
   Combine the terms:
   $-9p + p = -8p$.

3. 9. $-18 + 8x - 5$:
   Combine constants and variables:
   $-18 - 5 = -23$, so:
   $-23 + 8x$.

4. 10. $4w - 2x - 5w$:
   Combine like terms for $w$:
   $4w - 5w = -1w$, so:
   $-w - 2x$.

5. 11. $9r - 5r + 2 + r$:
   Combine $r$-terms: $9r - 5r + r = 5r$.
   Final expression:
   $5r + 2$.

6. 12. $-7m - 11 - 9 + 4m$:
   Combine like terms:
   $-7m + 4m = -3m$, and $-11 - 9 = -20$.
   Final expression:
   $-3m - 20$.

7. 13. $-a + 15 - 22 + 3a$:
   Combine like terms:
   $-a + 3a = 2a$, and $15 - 22 = -7$.
   Final expression:
   $2a - 7$.

8. 14. $27 + 13y - 20y + 5$:
   Combine $y$-terms: $13y - 20y = -7y$, and $27 + 5 = 32$.
   Final expression:
   $-7y + 32$.

9. 15. $4c - 9c + 16 - 5$:
   Combine $c$-terms: $4c - 9c = -5c$, and $16 - 5 = 11$.
   Final expression:
   $-5c + 11$.

10. 16. $19v - 15 + 4 - 7v + v$:
    Combine $v$-terms: $19v - 7v + v = 13v$, and $-15 + 4 = -11$.
    Final expression:
    $13v - 11$.

11. 17. $-x + x + 15y + 9x - 5y$:
    Combine $x$-terms: $-x + x + 9x = 9x$, and combine $y$-terms: $15y - 5y = 10y$.
    Final expression:
    $9x + 10y$.

12. 18. $16a + 3b - 13a - 11a + 4b$:
    Combine $a$-terms: $16a - 13a - 11a = -8a$, and $b$-terms: $3b + 4b = 7b$.
    Final expression:
    $-8a + 7b$.

13. 19. $18 - 2r + s - 25 - 9r + 15s$:
    Combine $r$-terms: $-2r - 9r = -11r$, combine $s$-terms: $s + 15s = 16s$, and constants: $18 - 25 = -7$.
    Final expression:
    $-11r + 16s - 7$.

14. 20. $-9d - 17 - 4 + 5c - 26 + 12d$:
    Combine $d$-terms: $-9d + 12d = 3d$, combine constants: $-17 - 4 - 26 = -47$, and $c$-term remains $5c$.
    Final expression:
    $3d + 5c - 47$.

Final Answers Recap:

1. $16k$
2. $-8p$
3. $-23 + 8x$
4. $-w - 2x$
5. $5r + 2$
6. $-3m - 20$
7. $2a - 7$
8. $-7y + 32$
9. $-5c + 11$
10. $13v - 11$
11. $9x + 10y$
12. $-8a + 7b$
13. $-11r + 16s - 7$
14. $3d + 5c - 47$

Do you need further explanations on any specific problem? Let me know!

Here are 5 related questions you might want to explore:

1. How do you combine like terms involving multiple variables?
2. What happens when all variables cancel out in an equation?
3. How do you handle distributive property before combining terms?
4. How do you simplify algebraic expressions with parentheses?
5. How do you solve algebraic expressions with exponents?

Tip: Always combine like terms carefully by grouping variables and constants separately to avoid mistakes.