(I should just solve them but could someone also show me how I can check if they are right?)
It would be great if someone could help me with those three problems. 


 To check it, notice that 

Substitute in 1.4 and 1.6, If 1.5 is
correct then 1.4 should check because it
is slightly less than "<",  and 1.5
should NOT check because it is slightly
greater than ">" .

Substituting 1.4



So 1.4 checks.

Now substitute 1.5



1.6 doesn't chack, and
it shouldn't because it
is greater than 


3x+1>10 



So 3.1 should check, but 2.9
should not check.

1<3x+2<12

 

To check, notice that  is -.3333
Therefore,
-.4 should not check, and -.2 should check.

Also notice that  is 3.333
Therefore,
3.2 should check, and 3.4 should not check. 

Edwin