That is, all cartons are converted into wooden cases: 6/2=3.

That is, * * * has a wooden box 2+3=5.

Each wooden case contains: 300/5=60.

Then 60/2=30 per case.

Each wooden case contains more than cartons: 60-30=30 pieces.

or

You can understand it this way ∵2 wooden cases =4 cartons.

∴ Total number of cartons =4+6= 10 (PCs)

Every carton is packed.

300÷ 10=30 (piece)

Each wooden case contains 30×2=60 pieces.