Answer:
-2 < x < 1
Step-by-step explanation:
Given inequality:
[tex]1 < x+3 < 4[/tex]
[tex]\textsf{If $a < u < b$ \;then\; $a < u$ \;and \;$u < b$}:[/tex]
Case 1
[tex]\implies 1 < x+3[/tex]
[tex]\implies 1-3 < x+3-3[/tex]
[tex]\implies -2 < x[/tex]
[tex]\implies x > -2[/tex]
Case 2
[tex]\implies x+3 < 4[/tex]
[tex]\implies x+3-3 < 4-3[/tex]
[tex]\implies x < 1[/tex]
Combine the intervals:
[tex]-2 < x < 1[/tex]
