The answer is 800.
To find this, multiply 10 times 8 to find the number you are dividing. (80) now, multiply 80 by 10. (800)
1/10 of 800 is 80, which is ten times as much as 8.
The value of y would be 20 times more valuable than 12 because the pattern for this table is y=20x. Let me know if I'm right :)