Question

A group of 45 people attended a ball game. There were twice as many children as adults in the group. Set up a system of equations that represents the numbers of adults and children who attended the game and solve the system to find the number of children who were in the group.

Answer 1

The system of equations that represents the numbers of children and adults looks like this: A= children and B= adults so A+B = 45 (or the total of both children and adults.
Since there were twice as many children as adults, then B+2A = 45.

Answer 2

Number of Adults = a
Number of children = 2a

Number of people in a group = 45

so
a + 2a = 45
3a = 45
a = 15

Number of Adults = 15
Number of children = 30