subtract 3 from both sides:
[tex]\dfrac{1}{2}(3-x)<-10[/tex]
Multiply both sides by 2:
[tex]3-x<-20[/tex]
Subtract 3 from both sides:
[tex]-x<-23[/tex]
Change sign to both sides (this implies that you should also change the inequality sign):
[tex]x>23[/tex]
