On one side of a street are even numbers and on the other side are odd numbers. No. 1 is exactly in front of No. 2. My house is No. 9. From my house, a man comes up from No. 2 and knocks at the door, five doors beyond the house infront of me. What is the No. of that house?

Options

A. 18
B. 20
C. 22
D. 26

Explanation

To solve the problem step by step, let's break down the information given in the question:

1. **Understanding the Layout**:
- On one side of the street, we have odd-numbered houses: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, etc.
- On the opposite side, we have even-numbered houses: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, etc.
- It is stated that house number 1 is directly in front of house number 2.

2. **Identifying Your House**:
- Your house is number 9, which is an odd number.
- The house directly in front of you (number 9) is house number 10 (the even number).

3. **Finding the Starting Point**:
- A man comes from house number 2 (which is on the opposite side of the street).
- He will knock at a house that is 5 doors beyond the house directly in front of your house (which is house number 10).

4. **Calculating the Target House**:
- Starting from house number 10, we count 5 doors beyond:
- 1 door beyond 10 is 12
- 2 doors beyond 10 is 14
- 3 doors beyond 10 is 16
- 4 doors beyond 10 is 18
- 5 doors beyond 10 is 20

5. **Conclusion**:
- Therefore, the house number where the man knocks is house number 20.

### Final Answer:
The number of that house is **20**.