Solution
For this case let :
x= number of adults
y= number of children
We can create the following equations:
x +y =8
5.5 x + 3.0 y=36.50
Then we can solve for x and we got:
x = 8-y
And replacing in the second equation we got:
5.5*(8-y)+ 3y = 36.50
44 -5.5y +3y = 36.50
44-36.50 =2.5y
7.5 =2.5y
y= 3
And for x we got:
x = 8- 3=5
Then the solution would be:
5 adult tickets