A convex lens of focal length f forms an image which is 13/ times the size of the object. Then, the distance of object from the lends is

Explanation

Image is real so `m = (v)/(u) = -(1)/(n) implies v = -(u)/(n)`
from lens formula `(1)/(v) - (1)/(u) = (1)/(f) implies (1)/(-(u)/(n)) - (1)/(u) = (1)/(f) implies (-(n+1))/(u) = (1)/(f) implies u = -f(1+n)`