Doubt

Hello Sir

I am having problems with accounting to the labour

Firstly-
When the say 601 units-650 units – is it actually 49 units or 50 units ( a very sill question but just wanted to be sure)

Secondly- I am super confused with overtime payment and overtime preimium and when is what a direct labour cost . In some questions they say that the overtime payments for direct labour is a direct cost

Thirdly- What is this time and quarter and how do we calculate the direct wages with that