A tank can be filled by a pipe A in five hours, pipe B takes seven hours to fill the same tank.pipe C takes ten hours to empty the tank.If all the pipes are left running simultaneously find how long they will take to fill the tank.Question b of the same starting with an empty tank, pipe A and C are left running for 6 hours while pipe B is closed.How long does it take pipe B to fill the remaining part of the tnk