X=number of children tickets
Y=number of adult tickets
X+y =162
6.4x+9.5y=1306.5
Y=162-x
Substitute
6.4x+9.5(162-x)=1306.5
6.4x+1539-9.5x=1306.5
-3.1x=-232.5
X=75
75+y=162
Y=162-75=87
So there were 75 child tickets and 87 adult tickets sold.
Hope that helps.
