no need to go in for all the books. Kaplan and OG should do. And ofcourse u have the NET. u can find hella lotta info out on the net. so keep scanning. if u want a lotta practice then manhatan gmat and princeton books should be good. No need to get other matls.
U can start off with kaplan. get the kaplan verbal workout. its a good book for building basics. then u can go to the kaplan premier edition. then onto OG. (official guide). Its the bible for gmat.
BTW, when are u plannin to take up the gmat???
Can u please explain me how in the figure you have calculated ON = 100 - 2d.
MO is given to be 20 ( i think u have taken MN to be 20)
And hw can the point N be before O . Speed of car X is more than that of Y. So N should be after O.