Alright, lets get started.
Jim was thinking of a number.
Suppose the number Jim was thinking, is x.
Jim adds 20 to it means number will be = [tex]x+20[/tex]
And Jim doubles it, means [tex]2*(x+20)[/tex]
Jim gets 99.2 and as per us, he gets [tex]2*(x+20)[/tex]
So, making them equal
[tex]2(x+20)=99.2[/tex]
[tex]2x+40=99.2[/tex]
Subtracting 40 in both sides
[tex]2x+40-40=99.2-40[/tex]
[tex]2x=59.2[/tex]
[tex]x=29.6[/tex]
It means the original number is 29.6. : Answer
Hope it will help :)