How to rewrite 7(3 + 3 + 3) + 1 =

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

Is this a polynomial function? i need to know asap

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?