A problem states: "There are 9 more children than parents in a room. There are 25 people in the room

A problem states: "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?"

Let the number of children be c. Let the number of parents be p

We're given:

1. c = p + 9 (9 more children than parents)
2. c + p = 25

to solve this system of equations, we plug equation (1) into equation (2) for c:
(p + 9) + p = 25

Group like terms:
2p + 9 = 25

To solve this equation for p, we type it in our search engine and we get:
p = 8