½ofthe distance the horse travelled alonewith velocity 12 km/h and then the poor thing was harnessed into a carriage andtraveled the ½ of the distance withvelocity 4 km/h

what is the average velocitywith which the horse would travel thewhole distance at the same time?

6 km/h

Explanation:

For the fist half we must have a distance travelled and  the time  that this distance was travelled in, we will call this d1, and t1. For the second half we must also have a distance and a time: d2 and t2.

If we say that the total distace was 'x'

Now, let's find t1 and t2.

for the fist half the horse was traveling at a velocity of 12 km/h, using

We have for t1:

And for t2, since the horse now is traveling at 4 km/h:

And finally we can find the average velocity, using the formula:

Thus, replacing the values we found:

he made 11 calls in one day