Question

which number is a solution of the inequality 12 < y(8-y)

Answer 1

The answer is: 2 < y < 6.
To get this answer, do the following steps:
Step #1 - First, find all the critical points of the inequality.
Step #2 - Last, check intervals in between critical points. (Meaning make sure you test the values in the intervals to see if they work.)

Answer 2

$12 \ \textless \ y(8-y)$