Explain how to find the maximum/ minimum of a quadratic function

Mindy bought 5/8 pound of almonds and a 3/4 pound of walnuts.which pair of fraction cannot be used to find how many pounds of nuts she bought in all.

Adele is five years older than timothy. in three years, timothy will be 2/3 of adele’s age. what is adele‘s current age?

Apassenger train and a freight train leave san jose at 3pm, traveling in the same direction. the passenger train is going three times as fast as the freight train. at 6pm they are 240 miles apart. how fast is each travelling? explain your answer and show your