Which set of data would be best modeled by a quadratic function?

Two sides of a triangle mesure 20cm and 30cm. what is the measure of the third side

Subscriptions to a popular fashion magazine have gone down by a consistent percentage each year and can be modeled by the function y = 42,000(0.96)t. what does the value 42,000 represent in the function?

What expression is equivalent to 42x-56y