Image ki velocity to 2v ho jata h .. Aapne negative of object velocity btaya . im confuse plz clear it

Sir here u said that x+y =90 but x+y is the distance BTW object and screen and in the question it has been said the distance BTW image and screen is 90cm ?so how can we write x+y=90

Focal length of M1 is 20 cm and that of M2 is 30cm

Q)find the position of 2nd image taking first reflection from M1.

What possible question can be asked from cochy's formula?

Sir please explain illustration 3.