A red ticket is equal to 10 blue tickets, and a yellow is equal to ten red tickets, so a yellow ticket is also equal to 10 * 10 = <<10*10=100>>100 blue tickets.
It takes 10 yellow tickets to win a Bible, or 10 * 100 = <<10*100=1000>>1000 blue tickets.
Tom has 8 yellow tickets, which are worth 8 * 100 = <<8*100=800>>800 blue tickets.
He also has 3 red tickets, which are worth 3 * 10 = <<3*10=30>>30 blue tickets.
Added with his 7 blue tickets, he has 800 + 30 + 7 = <<800+30+7=837>>837 blue tickets' worth of tickets.
So he still needs to earn 1000 - 837 = <<1000-837=163>>163 blue tickets.
#### 163