How to write 3.4 in expend form

What does x = in this equation x+3+2x=x+5

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

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