Answer:
$140
Explanation:
Given: Ticket cost $28 each. Zach's mom has a coupon for half-off. Both of Zach's parents are going plus 8 children including Zach. 
To find: The total ticket cost for the group.
Solution: 
We have,
Number of children going is 8, and two parents. So, total number people going at the amusement park is 

Cost of each ticket is $28
So, total cost 

It is given that Zach's mom has a coupon for half-off. 
After applying the coupon, the total cost is 

Hence, after applying the coupons the total ticket cost for the group is $140.