A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of preparing a personal budget. It sets up the subject without going into details. It does not use any pronouns or definite articles that refer to previous ideas. Why other lines are not chosen? Paragraph 2 starts with "Next," which shows it is not independent. Paragraph 3 starts with "By subtracting," which needs context. Paragraph 4 starts with "Next," which also shows it is not independent.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the topic of budgeting. It gives a final thought on the importance of reviewing and adjusting the budget.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it uses the word "Next". This shows a logical order in the steps of budgeting.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 logically because it explains what to do after listing expenses. It shows a clear flow of ideas.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it talks about the next step after knowing how much money is left. It continues the topic of managing finances.