We have 2 containers of same height, one containing 3 gallons, the other 4 gallons.
Measure 22/7 gallons in the 4 gallon container.
We'll suppose here :
The containers are rectangular, transparent.
We are allowed only 2 pours, all what we pour out is lost, we have only these two containers,
neither scales, nor any other measure instrument, pencil to mark the containers and s.o.