6. Variant 1. In the kindergarten, 5 children eat porridge every day, 7 children eat porridge every other day, and the rest never eat porridge. Yesterday, 9 children ate porridge. How many children will eat porridge today?
Answer: 8.

Solution. Of the 9 boys who ate porridge yesterday, 5 boys eat it every day, so the remaining $9-5=4$ eat it every other day. Therefore, these four will not eat porridge today, while the other $7-4=3$ of those who eat every other day will. So today, these three, as well as the five who always eat porridge, will eat it. We get the answer $3+5=8$.