Answer:
(i) 240 s
(ii) 20 min
Step-by-step explanation:
(i) Just look at the times for X and Y after each round, when is the first time, that the times match? In seconds
X: 60, 120, 180, 240 ...
Y: 80, 160, 240, ....
So they meet at the starting point after 240 seconds.
X has done 3 laps and Y 4 laps at this time.
(ii)
To answer this question: Let x be the number of laps that Y has done.
If X has done 5 laps more the following must be true:
60 * (x + 5) = 80x
60x + 300 = 80x
300 = 20x
x = 15
Therefore Y has done 15 laps at the time, which results in:
80 * 15 = 1200 seconds - or 20 min.
At the same time
60 * 20 = 1200 seconds gives the same outcome
