Need please

a.) On a map of scale 1cm = 50m with a contour interval of 1.5m,two adjacent contour lines are 1.37cm apart. What is the slope of the ground in percent? b.)The distance scaled on a 1:10,000 map between two adjacent contours is 25mm. Determine the slope of the ground in mils if the contour interval is 2 meters. I c.) On a map whose scale is 1/6000, how far apart would 1/2 m contours be on a uniform slope of 4%