Answer: 21 new children have come.
Step by step explanation:
Data :
- In the schoolyard we were = 80 children playing soccer
- After a while more children signed up = and there were 22 children
- How many new children have come = ?
We simply have to subtract the number of children playing from the number of children who arrived after a while:

We check:

Rpt: 21 new children have come.