Two metal rods made of steel and copper have coefficients of linear expansion 1.1 10⁻⁵ ~K ⁻¹ and 1.7 10⁻⁵ ~K ⁻¹ respectively. At room temperature (300 ~K ) , the steel rod is 4 cm longer than the copper rod. If the difference in their lengths remains same at all temperatures, then the lengths of the steel and copper rods respectively (at 300 K ) are