Final answer:
The equilibrium price for the T-shirts at this concert is $12.
Step-by-step explanation:
To find the equilibrium price, we need to set the quantity demanded equal to the quantity supplied. So, we can set the two functions equal to each other: -300 + 50p = 960 - 55p.
Now we can solve for p:
105p = 1260
p = 12
Therefore, the equilibrium price for the T-shirts at this concert is $12.