How do you add time?

This is what I have now 7:00A.M. 12:00P.M. 12:30P.M. 3:30P.M. = 11:00P.M.

This is what I would like 7:00A.M. 12:00P.M. 12:30P.M. 3:30P.M.  =   8 HOURS
TOTAL