A school bus starts from Rest House Stop and reaches the school, covering a straight-line distance of 18km in 25min without changing its speed.
a. (i) Calculate the speed of the bus in km/h.
b. (ii) Express this speed in m/s.
c. (iii) If a distance–time graph were drawn for this journey, what numerical value would the slope of the straight line represent? State its value using the result obtained in part (i).