Leigh-Mari walks 10 kilometres to a waterfall at an average speed of 3 kilometres per hour.
(a) Write down, in terms of r, the time taken in hours.
(b) Leigh-Mari returns from the waterfall but this time she
walks the 10 kilometres at an average speed of (x+1)
kilometres per hour. The time of the return journey is
30 minutes less than the time of the first journey. Write
an equation in x and show that it simplifies to
2 + 1 - 20 = 0.
(c) Solve the equation x2 + - 20 = 0.
(d) Find the time Leigh-Mari takes to walk to the waterfall,​