Mat starts out 10 m behind Norman.

Every time Mat runs 5 m, Norman runs 3 m. Let’s count this configuration as one block.

For every block completed, the gap/distance between Mat and Norman decreases by 2 m (because Mat runs faster to catch up with Norman).

Since 10/2 = 5, we can conclude that we need five blocks of time/movement for Mat to catch up with Norman.

By this time, the distance moved by Mat
= 5 x 5
= 25 m

An alternative method for P6 would be listing.

Mat starts 10m behind Norman.

We can say Mat starts at 0m and Norman starts at 10m.

List increases in multiples of 3 for Norman and multiples of 5 for Mat. Look for the value where the two have the same distance and the same number of increases.

Mat
0 5 10 15 20 25 30 35 ...

Norman
10 13 16 19 22 25 28 31 ...


You can see at 25m, Mat has caught up with Norman.