Exercise 2. Over a certain number of days, it was observed that on each day it rained in the morning, it was sunny in the afternoon, and that on each day it rained in the afternoon, it had been sunny in the morning.

During the observation period, it rained on 15 days, and it was sunny 8 mornings and 13 afternoons.

How many mornings did it rain?
## Solution to Exercise 2

According to the statement, it did not rain for a full day during the period in question. Since it rained for 15 half-days and was sunny for 21 half-days, this gives a total of 36 half-days, and allows us to assert that we are in fact considering a period of 18 days.

Since it was sunny on 8 of the 18 mornings, there were therefore 10 rainy mornings.