Question

"There are 9 more children than parents in a room. There are 25 people in the room in all. How many children are there in the room?" What are the unknowns in this problem?

Answer 1

x = parents 
x+9 = children 

x + x + 9 = 25
2x = 25 - 9
2x = 16
x = 16/2
x = 8 parents 

8 + 9 = 17 children 

Unknowns in this problem are the number of parents and the number of children.