Given:
Admission to the local movie theater is $3 for each child and $7 for each adult.
A group of 12 people pay $64 admission.
To find:
The number of children in a group.
Solution:
Let the number of children be x and number of adults be y.
According to the question,
Total persons : [tex]x+y=12[/tex] ...(i)
Total cost : [tex]3x+7y=64[/tex] ...(ii)
Multiply equation (i) by 7 and subtract the result from (ii).
[tex]3x+7y-7(x+y)=64-7(12)[/tex]
[tex]3x+7y-7x-7y=64-84[/tex]
[tex]-4x=-20[/tex]
Divide both sides by -4.
[tex]x=5[/tex]
Therefore, the number of children is 5.
