1.) Let's say that the circle on the graph below represents x. The arrow is pointing to all the numbers greater than x, which happens to be on -2. If it points right, this means that x can equal to any number greater than -2. So your answer is x > -2.
2.) For inequalities such as these, you can simplify just like what you do for normal equations. Let's isolate x.
[tex]x - 7 > 10[/tex]
--> [tex]x > 10 + 7[/tex]
---> [tex]x > 17[/tex]
3.) [tex]3x \leq 21[/tex]
--> [tex]\frac{3x}{3} \leq \frac{21}{3}[/tex]
---> [tex]x \leq 7[/tex]
4.) [tex]5a - 2 < 18[/tex]
--> [tex]5a < 18 + 2[/tex]
---> [tex]5a < 20[/tex]
----> [tex]\frac{5a}{5} < \frac{20}{5}[/tex]
-----> [tex]a < 4[/tex]
5.) [tex]2t + 8 \geq -4(t + 1)[/tex]
--> [tex]2t + 8 \geq -4t - 4[/tex]
---> [tex]2t + 4t \geq -8 - 4[/tex]
----> [tex]6t \geq -12[/tex]
-----> [tex]t \geq -2[/tex]
