Answer :
let x,y and z represent no. of pens with mohit,ram and sam respectively
so
x+y=20
z-y=7..(1)
x-z=2...(2)
therefore add (1) and (2)
x-y=9
x+y=20
-----------------
2x=29
x=29/2
y=11/2
there can't be 11/2 pens please check ur question
so
x+y=20
z-y=7..(1)
x-z=2...(2)
therefore add (1) and (2)
x-y=9
x+y=20
-----------------
2x=29
x=29/2
y=11/2
there can't be 11/2 pens please check ur question
Approx answer Will be 5 or 6 pens.. cos the question has some mistake..