Answer:
x > 
 OR x > -2.33
Explanation:
The first step is to subtract 8 from both sides, like so:
-3x + 8 < 15
 - 8 - 8
__________
-3x < 7
Divide both sides by -3:
x < 
 
Whenever, you multiply/divide by a negative number, you must flip the inequality sign around. In this case, we divided by a negative:
x > 
 OR x > -2.33