Help me figure this out

h add your notes, read the ex When you breathe, the air entering your lungs has a positive velocity and the air exiting your lungs has a negative velocity. The relationship between velocity, in litres of air per second (L/s), and time, in seconds, for an adult at rest, can be modelled by the graph shown. a) What is the equation of the midline? What does it represent in this situation? b) What is the amplitude of the function? c) What is the period of the function? What does it represent in this situation