need help with this answer 

Suppose Devin and Leslie throw a baseball into the air. The height of Devin's baseball is given by h(t)=−16t2+79t+5, where h is in feet and t is in seconds. The height of Leslie's baseball is given by the graph below:

Devin claims that his baseball went higher than Leslie's, and Leslie says that her baseball went higher.

(a) Who is right?

(b) How long is each baseball airborne?

(c) Construct a graph of the height of Devin's throw as a function of time on the same set of axes as the graph of Leslie's throw (if not done already), and explain how this can confirm your claims to parts (a) and (b). You do not need to submit the graph but you must be specific in your explanation.

You must show all your work to receive any credit.

This is were I am so far not sure if this is correct ( please help a and b thank you 

 H(t)=-16t^2+79t+5

=-16(t^2)-(79/16t-5/16)

=-16(t^2-29/16t+(79/(2)(16))^2-(79/(2)(16)^2 -5/16)   

=-16(t^2-79/(2)(16))^2-(-16)(79/(2)(16))^2+5

=(t^2-79/(2)(16))^2+