Consider the figure shown, what will the total magnification after two successive reflections first on M1 and then on M2 ?

Two reflections mean, the first image from M1 to the object for M2 :Using mirror formula :1v+1u=1fFirst reflection on M1 :u=−30cm;f=−20cm:1−30+1v=1−20⇒v=−60cmm1=-vu=-2The first image forms 60 cms in front of M1, So, the object for M2 is 20 cms behind the mirror : for second reflection :u=+20cm;f=+10cm1v+120=110⇒v=20cmm2=-vu=-1Total magnification is given by :mtot =m1×m2=-2-1=2