Answer:
[tex]f(t)=9t+72[/tex]
Step-by-step explanation:
Matt has already sold $72 worth of tickets to the benefit concert.
He had 6 tickets left to sell at $9 per ticket.
We can write the function of total amount earned as:
[tex]f(t)=9t+72[/tex] ; where t = 6
f(t) represents the total amount earned by Matt by selling all tickets.
So total amount will be :[tex]9(6)+72=126[/tex] dollars