Write the standard equation of each circle,

Quadrilateral abcd in the figure below represents a scaled-down model of a walkway around a historic site. quadrilateral efgh represents the actual walkway. abcd is similar to efgh. what is the total length, in feet of the actual walkway?

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x