A route up a mountain is 20 km long.
John followed this route at an average speed of x km/h.
(a) Write down an expression, in terms of x, for the number of hours he took to walk up the mountain
(b) He came down the mountain by a different route. The length of this route was 25 km.
[1]
His average speed coming down the mountain was 2 km/h greater than his average speed going up the mountain.
Write down an expression, in terms of x, for the number of hours he took to walk down.
[1]
(c) It took John 1 hours less to come down than to go up.
Write down an equation in x, and show that it simplifies to
3x2+16x-80=0.