I see you've uploaded a photo containing some algebraic expressions to simplify. Let's go through the problems and simplify them.

Simplifying Algebraic Expressions:

1. Problem 16:
   $12g + 9g$
   Combine like terms:
   $(12g + 9g) = 21g$

2. Problem 17:
   $11x + 9 - 7$
   Simplify the constants:
   $11x + (9 - 7) = 11x + 2$

3. Problem 18:
   $8s - 11s + 6s$
   Combine like terms:
   $(8s - 11s + 6s) = 3s$

4. Problem 19:
   $4b - 24 + 19$
   Simplify the constants:
   $4b + (-24 + 19) = 4b - 5$

5. Problem 20:
   $4p = 5p - 30p$
   Combine like terms on the right-hand side:
   $4p = (5p - 30p) = 4p = -25p$

6. Problem 21:
   $4.2v - 5 = 6.5v$
   To simplify, bring all terms with $v$ to one side:
   $4.2v - 6.5v = 5$
   $-2.3v = 5$
   Divide both sides by $-2.3$:
   $v = \frac{5}{-2.3} \approx -2.17$

7. Problem 22:
   $8 + 4a + 6.2 - 9a$
   Combine like terms:
   $(8 + 6.2) + (4a - 9a) = 14.2 - 5a$

8. Problem 23:
   $\frac{2}{5}y - 4 + 7 - \frac{9}{10}y$
   Combine constants and fractions:
   $(-4 + 7) = 3$
   Convert to a common denominator for $y$ terms:
   $\frac{2}{5}y - \frac{9}{10}y = \frac{4}{10}y - \frac{9}{10}y = -\frac{5}{10}y = -\frac{1}{2}y$
   Final expression:
   $-\frac{1}{2}y + 3$

9. Problem 24:
   $\frac{2}{3}c - 9.5 + 14c + \frac{3}{10}$
   Combine constants and fractions:
   $(-9.5 + \frac{3}{10}) = -9.2$ (approximately)
   Combine $c$ terms:
   $\frac{2}{3}c + 14c$
   Convert to a common denominator:
   $\frac{2}{3}c = \frac{42}{3}c$
   $\frac{42}{3}c + \frac{2}{3}c = \frac{44}{3}c$
   Final expression:
   $\frac{44}{3}c - 9.2$

Would you like more detailed explanations on any of these steps or have any specific questions?

Here are 5 related questions for practice:

1. How do you simplify an expression with multiple variables?
2. What are the steps to solve an equation with fractions like in problem 23?
3. How can you combine terms that have different coefficients?
4. What is the process of converting fractions to a common denominator?
5. How would you handle an equation where all terms are on one side of the equal sign?

Tip: When simplifying expressions, always combine like terms first, which means grouping together the terms that have the same variable raised to the same power.