What is the value of a in the equation 5a-10b=45, when b=3

Abank gives 6.5% interest per year. what is the growth factor b in this situation?

If y varies directly as x2 and y=6 when x=6, find the constant of variation.

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?