the lens of a camera has a focal lenght (F) THAT SATIFIES THE EQUATION
F= d0 xdk /(d0 + dk)
where d0 is the distant from the object to the lens, and dx is the distant from the lens to thr flim.
if an object is 60cm from the cameralens and the lens is 10cm from the flim, ehat is the approximate focal lenght, in centimeter, of the lens?