Questions

ADDRESS is what the kind of dress can never be worn by anyone.

The monomer of polythene is ethylene.

The logic in the given puzzle is 

4 + 4 = 4 * 4+1 = 4 * 5 = 20

5 + 5 = 5 * 5+1 = 5 * 6 = 30

6 + 6 = 6 * 6+1 = 6 * 7 = 42

7 + 7 = 7 * 7+1 = 7 * 8 = 56

Similarly

9 + 9 = 9 * 9+1 = 9 * 10 = 90.

If you want bonus points, make sure you address each side of this tricky two-part question. 

The first part is addressing how you make sure you greet each and every customer who enters the store, giving them personal attention.  

The second part is how you would actually greet them – what would you say to them? Would you alert them of your newest products, ask if they’re looking for anything in particular or need guidance while shopping, or alert them to who they can reach out to if they require any assistance in various departments?

We know that,

The equivalent K =  L1 + L2L1K1+L2K2

where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.

But here L1 = L2 = L (say)

Then K = L+L/(L/K1 + L/K2)  =  2K1K2K1+K2