Hong must have travelled 240 m more than Jeya, simply because Hong travelled 120 m past the centre point and Jeya travelled 120 m less than the centre point.

Now, because Hong travelled at a faster rate than Jeya by 15 m / min, and they left their respective houses at the same time and reached the library at the same time, 16 min must have passed (240/15 = 16).

This is because for every 1 minute passed, Hong travelled 15 m further than Jeya, and therefore for 16 min passed, Hong travelled 240 m further than Jeya.

So, they both must have taken 16 min to reach the library.

Jeya travelled at a speed of 70 m per min.

Total distance from Jeya’s house to the library
= 70 x 16
= 1120 m
= 1 km 120 m