\textbf{158.} An object is placed once at distance $P$ and once at distance $P + 8$ cm from a lens, and in both cases the image is located at the same distance from the lens. If the image size is 5 times the object size, what is the power of this lens in diopters?
\[
(4)\ -5 \qquad (3)\ -2 \qquad (2)\ +5 \qquad (1)\ +2
\]