There is an unknown number of people at the table at the beginning of lunch. Then...
3 more people joined the group.
Then the entire group divided into 2 groups, and
one group left and went outside,
of the total students were left in the lunchroom
5 people joined the group in the lunchroom.
The total number of people in the lunchroom at the
end of lunch was 10

a. Write the equation you can create to show this situation.

b. How many people were at the table at the beginning of lunch? Explain how you know.