A student stays at a distance of 3.5 km from his college and he travels the distance at a constant speed. If he stops for breakfast for 8 min after a distance of 2 km which he travelled with constant speed, he has to increase his speed by 3 km/hr to reach in the usual time. One day, he starts off 5 min late and stops for breakfast for 5 min, by how much should he increase his speed?