How do you decide whether to take the positive or negative square root?

Empty box + box + empty box fill in the box is equal to 30 how

Ms.ortiz sells tomatoes wholesale. the function p(x)=-80x^2+320x-10, graphed below, indicates how much profit she makes on a load of tomatoes if she makes on a load of tomatoes if she sells them for 4-x dollars per kilogram. what should ms.ortiz charge per kilogram of tomatoes to make on a load of tomatoes?

Graph the equationy= x+3[tex]y = x + 3[/tex]