First, we have to make [tex]w[/tex] the subject of the equation:
[tex]w - 0.9 > -2.1\\w > -2.1 + 0.9\\w > -1.2[/tex]
This shows that [tex]w[/tex] is less than but not equal to [tex]-1.2[/tex]. So we are going to use an arrow that has a non-shaded circle. Since the symbol is the greater than symbol, or >, the arrow will point to the right. Thus, the arrow we choose will be the last arrow.
Now since we are comparing [tex]w[/tex] with [tex]-1.2[/tex], we place the arrow above the [tex]-1.2[/tex] point. That's how he place the arrow in the number line.
