Answer:
The number of children are 54, number of students are 84 and number of adults are 27.
Step-by-step explanation:
Let the number of children be [tex]x[/tex]
Let the number of students be [tex]y[/tex]
Let the number of adults be [tex]z[/tex]
As per question,
[tex]x+y+z=165\\5x+7y+12z=1182[/tex]
Now, adults are half of the children.
So, [tex]z=\frac{x}{2}\\x=2z[/tex]
Now, plug in [tex]x=2z[/tex] in the first two equations.
[tex]2z+y+z=165\\3z+y=165-----------------3\\\\ 5(2z)+7y+12z=1182\\10z+12z+7y=1182\\7y+22z=1182 ---------------- 4[/tex]
Multiply equation (3) by -7 and add it to equation (4).
[tex](3z+y=165)\times -7=-21z-7y=-1155\\\\-21z-7y+7y+22z=-1155+1182\\(22z-21z)+(7y-7y)=27\\z=27[/tex]
Solve for the remaining variables.
[tex]x=2z=2\times 27=54[/tex]
[tex]x+y+z=165\\54+y+27=165\\81+y=165\\y=165-81=84[/tex]
Therefore, the number of children are 54, number of students are 84 and number of adults are 27.