Solve using the addition & multiplication principles

Question

8x-13<-45
Solution {x]x__ __}

Answer 1

8x < -32
x < -4

I do not understand your {x]x__ notation

Answer 2

Solve the equation for x as if it were an equal sign. The only difference is if you multiply both sides by a negative number, the inequality sign has to be reversed:
8x-13<45
After that, give the answer in set notation {x|x<??} or in interval notation (-∞,??)