In borax number of `B-O-B` bonds are X and number of boron atoms are Y. Then `X+Y` is

Answer

To solve the problem, we need to determine the number of Boron-Oxygen-Boron (B-O-B) bonds (denoted as X) and the number of Boron atoms (denoted as Y) in the structure of borax, which is represented by the formula Na2B4O7·10H2O.

### Step-by-Step Solution:

1. **Identify the Structure of Borax**:
- Borax has the chemical formula Na2B4O7·10H2O.
- It consists of 4 boron (B) atoms and 7 oxygen (O) atoms.

2. **Count the Number of Boron Atoms (Y)**:
- From the formula, we can see that there are 4 boron atoms.
- Therefore, \( Y = 4 \).

3. **Identify the B-O-B Bonds**:
- In the structure of borax, the boron atoms are connected through oxygen atoms.
- Each pair of boron atoms is connected by an oxygen atom, forming B-O-B bonds.
- In the case of borax, there are 2 B-O-B linkages formed between the boron atoms.

4. **Count the Number of B-O-B Bonds (X)**:
- Since there are 4 boron atoms, we can visualize the connections:
- B1 connects to B2 through O1 (1 B-O-B bond)
- B2 connects to B3 through O2 (2 B-O-B bonds)
- B3 connects to B4 through O3 (3 B-O-B bonds)
- Thus, the total number of B-O-B bonds is \( X = 3 \).

5. **Calculate \( X + Y \)**:
- Now we can find \( X + Y \):
\[ X + Y = 3 + 4 = 7 \]

### Final Answer:
The value of \( X + Y \) is **7**.