A teacher who is teaching his own daughter is not a part of economic activity as the imputed value of such activities can not be calculated.

Gross profit = Net sales (total receipts) - Cost of goods  sold (total expenditure)

In other words it is the total receipt over total cost.

For private corporate sector, retained profits adjusted for non operating surplus/deficit is considered as net saving

Under the consideration of India economy, census of agriculture, is done by production method.