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The image shows an exercise asking to evaluate expressions for \( a = -2 \) and \( b = 3 \). Let's solve the given problems step-by-step:

### Problem a:
Evaluate: 
\[
3a^2 - 5b + 8
\]
Given: \( a = -2 \) and \( b = 3 \).

Step 1: Substitute \( a = -2 \) and \( b = 3 \) into the expression:
\[
3(-2)^2 - 5(3) + 8
\]

Step 2: Calculate \( (-2)^2 = 4 \):
\[
3(4) - 5(3) + 8 = 12 - 15 + 8
\]

Step 3: Simplify:
\[
12 - 15 + 8 = 5
\]

Thus, the result of part (a) is:
\[
\boxed{5}
\]

---

### Problem b:
Evaluate:
\[
\frac{7}{8} b - 5a
\]
Given: \( a = -2 \) and \( b = 3 \).

Step 1: Substitute \( a = -2 \) and \( b = 3 \) into the expression:
\[
\frac{7}{8} (3) - 5(-2)
\]

Step 2: Calculate \( \frac{7}{8} \times 3 = \frac{21}{8} \):
\[
\frac{21}{8} - 5(-2)
\]

Step 3: Calculate \( -5(-2) = 10 \):
\[
\frac{21}{8} + 10
\]

Step 4: Convert 10 into a fraction: \( 10 = \frac{80}{8} \):
\[
\frac{21}{8} + \frac{80}{8} = \frac{101}{8}
\]

Thus, the result of part (b) is:
\[
\boxed{\frac{101}{8}}
\]

---

### Problem c:
Evaluate:
\[
\frac{a^2 + 28}{4} + 4a
\]
Given: \( a = -2 \).

Step 1: Substitute \( a = -2 \) into the expression:
\[
\frac{(-2)^2 + 28}{4} + 4(-2)
\]

Step 2: Calculate \( (-2)^2 = 4 \):
\[
\frac{4 + 28}{4} + 4(-2)
\]

Step 3: Simplify:
\[
\frac{32}{4} + 4(-2) = 8 - 8
\]

Thus, the result of part (c) is:
\[
\boxed{0}
\]

---

Do you want further details or have any questions? Here are 5 related questions for practice:

1. Evaluate \( 2a^2 - 4b + 10 \) when \( a = -2 \) and \( b = 3 \).
2. Simplify \( 6a + 7b^2 - 2ab \) for \( a = -2 \) and \( b = 3 \).
3. Evaluate \( \frac{5}{6} a + 3b^2 \) given \( a = -2 \) and \( b = 3 \).
4. Calculate \( 2a + 3b - 7 \) when \( a = -2 \) and \( b = 3 \).
5. Solve \( a^3 + b^3 \) for \( a = -2 \) and \( b = 3 \).

**Tip:** When substituting values, ensure the correct order of operations—solve exponents and parentheses first before multiplying and adding.

Evaluate each expression below if a = -2 and b = 3:
(a) 3a^2 - 5b + 8
(b) 7/8 * b - 5a
(c) (a^2 + 28)/4 + 4a

Learn how to evaluate algebraic expressions such as 3a^2 - 5b + 8, 7/8 * b - 5a, and (a^2 + 28)/4 + 4a by substituting the values of a = -2 and b = 3. This step-by-step solution explains key algebraic concepts suitable for students in Grades 7-9.

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