Answer: 250 m
Explanation:
Given
Distance between Ursula and Velda house is 4 km or 4000 m
Ursula walks at the rate of

Velda walks at the rate of

Time taken by them to cover 4000 m is

Distance covered by them 15 min before they meet
Ursula

Velda

The total length covered by them is

They are
apart before they meet