PLZ help asap I really want an explanation cuz this is for a test and I need to know if it's right

What kind of bond pays interest which is exempt from tax?

What are the solutions of the system? solve by graphing. y = -x^2 -6x - 7 y = 2

The serenity and the mystic are sail boats. the serenity and the mystic start at the same point and travel away from each other in opposite directions. the serenity travels at 16 mph and the mystic travels at 19 mph. how far apart will they be in 3 hours?