A motorboat race is held in Bogasha river in Kenya over 3 stretches; P, Q and R. The maximum speeds allowed in stretches P, Q and R are 80 km/hr, 65 km/hr and 30 km/hr, respectively. The minimum speeds allowed over the 3 stretches are 50 km/hr, 40 km/hr and 15 km/hr, respectively. Each of the stretches is 4 km in length and speed over a stretch is assumed constant. Current record for the race is 12 minutes 30 seconds. Abdul completes the first stretch at the minimum speed and is able to maintain the same speed in the second stretch also. If he takes 60% more time than the current record time, then his speed over the stretch R is approximately