We need to solve:
[tex]2.6+x<8.3[/tex]The first step is to subtract "2.6" on both sides:
[tex]\begin{gathered} 2.6+x-2.6<8.3-2.6 \\ x+2.6-2.6<5.7 \\ x<5.7 \end{gathered}[/tex]On the number line, we have:
Notice that the the dot must be on "5.7" and it must be an opened dot.