Which of the following sets are equal ?
`A={x:x inN,xlt4},B={1,2,3},C={1,3}`,
`D={x:x inN, x` is odd x < 5} , E = {1,2,3},
F={3,1}`.

Answer

To determine which of the given sets are equal, we will analyze each set and compare their elements.

### Step-by-Step Solution:

1. **Identify the elements of each set:**
- Set A: \( A = \{ x : x \in \mathbb{N}, x < 4 \} \)
- Set B: \( B = \{ 1, 2, 3 \} \)
- Set C: \( C = \{ 1, 3 \} \)
- Set D: \( D = \{ x : x \in \mathbb{N}, x \text{ is odd and } x < 5 \} \)
- Set E: \( E = \{ 1, 2, 3 \} \)
- Set F: \( F = \{ 3, 1 \} \)

2. **Evaluate Set A:**
- Since \( x \) is a natural number and \( x < 4 \), the elements of set A are \( 1, 2, 3 \).
- Thus, \( A = \{ 1, 2, 3 \} \).

3. **Evaluate Set B:**
- Set B is already given as \( B = \{ 1, 2, 3 \} \).

4. **Evaluate Set C:**
- Set C is given as \( C = \{ 1, 3 \} \).

5. **Evaluate Set D:**
- Set D includes natural numbers that are odd and less than 5. The odd natural numbers less than 5 are \( 1 \) and \( 3 \).
- Thus, \( D = \{ 1, 3 \} \).

6. **Evaluate Set E:**
- Set E is given as \( E = \{ 1, 2, 3 \} \).

7. **Evaluate Set F:**
- Set F is given as \( F = \{ 3, 1 \} \). Note that sets are unordered, so \( F \) is equivalent to \( \{ 1, 3 \} \).

8. **Compare the sets:**
- Sets A, B, and E all contain the elements \( \{ 1, 2, 3 \} \). Therefore, \( A = B = E \).
- Sets C, D, and F all contain the elements \( \{ 1, 3 \} \). Therefore, \( C = D = F \).

### Conclusion:
- The sets that are equal are:
- \( A = B = E \)
- \( C = D = F \)