The person can buy a maximum of three T-shirts to the group of friends.
In this case we have the case of a person that saved some money to go to the State Fair with a group of friends, the maximum number of T-shirts to be bought is derived from the money available after spending to get a ticket to get in to the fair. The number of T-Shirts is found by means of the following operation:
x = ($ 72 - $ 12) / ($ 20)
x = ($ 60) / ($ 20)
x = 3
The person can buy a maximum of three T-shirts for the friends.
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