Two converging mirrors of focal length 30 cm are 15 cm apart. If an object is placed 1 cm from mirror one, how far from mirror two will the second image be?
Have you calculated where the first image is? Consider rays going from the left to mirror 1. A virtual image will be formed at location di given by
1/di + 1/15 = 1/30
1/di = -1/30
di = -30, which would be 30 cm to the left of (behind) mirror 1. This acts as the source (object) for mirror 2, 45 cm away on the right. For the location of the second image, use
1/45 + 1/di = 1/30
1/di = 3/90 - 2/90 = 1/90
di = 90
That real image would be 90 cm in front of mirror 2.