Speed = $\frac{\mathrm{Distance}}{\mathrm{Time}}$

Distance = Speed x Time

Walking speed = 1$\frac{1}{2}$ km per hour

Walking speed = $\frac{\mathrm{1\; x\; 2\; +\; 1}}{2}$ km per hour

Walking speed = $\frac{\mathrm{2\; +\; 1}}{2}$ km per hour

Walking speed = $\frac{3}{2}$ km per hour

Walking distance = $\frac{3}{2}$ x 3

Walking distance = $\frac{9}{2}$ km

15$\frac{1}{2}$ km per hour = $\frac{\mathrm{15\; x\; 2\; +\; 1}}{2}$ km per hour

15$\frac{1}{2}$ km per hour = $\frac{\mathrm{30\; +\; 1}}{2}$ km per hour

15$\frac{1}{2}$ km per hour = $\frac{31}{2}$ km per hour

Distance by bus = $\frac{31}{2}$ x 2 = 31 km

Distance from village to Quamu = Walking distance + Distance by bus

Distance from village to Quamu = $\frac{9}{2}$ km + 31 km

31 = $\frac{31}{1}$

Distance from village to Quamu = $\frac{9}{2}$ km + $\frac{31}{1}$ km

Distance from village to Quamu = $\frac{\mathrm{1\; x\; 9\; +\; 2\; x\; 31}}{2}$ km

Distance from village to Quamu = $\frac{\mathrm{9\; +\; 62}}{2}$ km

Distance from village to Quamu = $\frac{71}{2}$ km

Distance from village to Quamu = 35$\frac{1}{2}$ km or 35.5 km

Distance = Speed x Time

Speed = 100 km per hour

Time = 6 hours 30 minutes = 6.5 hours

NOTE: 30 minutes is half of an hour = 0.5 hours

If calculating the duration (time taken to cover the trip) is difficult for you, change the time to 24 hours time format and calculate the difference

6:30 am = 6.5

1:00 pm = 13

Time taken = 13 - 6.5 = 6.5 hours

Distance = Speed x Time

Distance = 100 km/hour x 6.5 hour = 6.5 x 100km = 650 km

NOTE: the hour cancels each other