Final answer:
The equilibrium price for T-shirts at the concert is $16, while the equilibrium quantity is 600 T-shirts.
Step-by-step explanation:
The equilibrium price for T-shirts at the concert can be found by setting the quantity demanded equal to the quantity supplied.
To find the equilibrium price, we need to solve the equation D(p) = S(p).
Substituting the given equations for D(p) and S(p), we have 1000 - 25p = -200 + 50p.
Combining like terms and simplifying, we get 75p = 1200.
Dividing both sides by 75, we find p = 16.
Therefore, the equilibrium price for T-shirts at this concert is $16.
To find the equilibrium quantity, we can substitute the equilibrium price into either the D(p) or S(p) equation.
Using D(p), we have D(16) = 1000 - 25(16) = 1000 - 400 = 600.
Therefore, the equilibrium quantity is 600 T-shirts.