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Answer:


Step-by-step explanation:
Let x be the number of adult tickets and y be the number of children's tickets.
We are given that there are total 12 people. Therefore, we can set:

Moreover, we are given that an adult ticket costs $21.50 and a child's ticket costs $14.75, therefore, cost of x adult tickets will be
and cost of y children's ticket will be
. We can form the second equation by setting the total cost of tickets as:

Therefore, the required system of equations that could be used to find x and y will be:

