We are given that
child admission is $5.20 and
adult admission is $9.60.
Now let us say there were x children and y adults.
On Monday, 155 tickets were sold,
so x+y=155......................(1)
Total sales were of $1070.00
so 5.20x +9.60y = 1070.............(2)
substituting value of x=155-y from equation (1) in equation (2), we get
5.20(155-y) +9.60y=1070
806-5.20y+9.60y=1070
4.4y=264
y=60
Answer: 60 adult tickets were sold that day