A tangent section of highway has a -1.0 % grade and ends at station 0+145 and elevation 25m. it must be connected to another section of highway that has a -1.0 % grade and that begins at station 1+345 and elevation 40 m. the connecting alignment should consist of a sag curve, constant grade-section, and crest curve, and be designed for a speed of 80 km/h. What is the lowest grade possible for the constant grade section that will complete this alignment?