ab and ba are two 2-digit numbers then ab + ba is equal to :

1. 2ab

2. 11ab

3. 11(a + b)

4. none of these

In a 2-digit number ab and a > b then ab - ba is equal to :

1. 0

2. 9(a - b)

3. 9(b - a)

4. none of these

If a > b, then for two 3-digit numbers abc and cba; we have abc - cba equal to :

1. -27

2. -6

3. 6

4. none of these