1 minute is 40m, just multiply by 5 to get 5 minutes and 200m.
triangle's area is base * height / 2
with CD as the base, anywhere between A and B is the same height of 4cm (which results in the triangle's area being 10cm²). since the goal will be somewhere between B and C, place the P at B and add 2.5 seconds to get there.
lastly the triangle's height needs to be 2cm so advance the P 2cm in 1 second to get the result of 3.5 seconds.