## Simplifying the Expression: (a^2 - 3a)(a^2 - 3a + 7) + 10

This expression involves a combination of multiplication and addition. Let's break it down step by step:

### 1. Recognizing the Pattern

Notice that the first part of the expression, **(a^2 - 3a)**, appears twice. This suggests a substitution could simplify the process.

### 2. Substitution

Let's substitute **x = (a^2 - 3a)**. Our expression now becomes:

**x(x + 7) + 10**

### 3. Expanding and Simplifying

Expanding the expression:

**x^2 + 7x + 10**

Now, we can factor this quadratic expression:

**(x + 5)(x + 2)**

### 4. Resubstitution

Substituting back **x = (a^2 - 3a)**:

**(a^2 - 3a + 5)(a^2 - 3a + 2)**

### 5. Final Result

Therefore, the simplified form of the expression **(a^2 - 3a)(a^2 - 3a + 7) + 10** is **(a^2 - 3a + 5)(a^2 - 3a + 2)**.