Ineed on subtracting and adding integers.. can someone explain in deep explanation?

Water flows at a steady rate from a tap. its takes 40 seconds to fill a 4 litre watering can from the tap. the rate at which water flows from the tap is halved. complete: 4 litres into cm3

Drag the tiles to the correct boxes to complete the pairs. not all tiles will be used. match each division expression with the correct quotient.

What is the rate for one gallon of gasoline