Answer:
8 number of visits will be the total cost of the visits (including the price of the discount card) be less expensive for a family of 2 adults and 1 child if they have purchased the discount card
Step-by-step explanation:
Price without Discount Card Price with Discount Card
Ticket (12 & Under) $10 $8
Adult's Ticket $15 $12
Let x be the number of visits
Price without discount card for 2 adults and 1 child ticket
Price without discount for x visits = 
Price with discount for x visits =
Now to find For what number of visits will the total cost of the visits (including the price of the discount card) be less expensive for a family of 2 adults and 1 child if they have purchased the discount card
57+32x< 40x
57<8x
7.1<x
So, 8 number of visits will be the total cost of the visits (including the price of the discount card) be less expensive for a family of 2 adults and 1 child if they have purchased the discount card