Объяснение:

-3 < х < 5

-6 + 9 < 2x + 9 < 10 + 9

3 < 2x + 9 < 19

[tex]\displaystyle\bf\\-3 < x < 5\\\\-3\cdot 2 < x\cdot 2 < 5\cdot 2\\\\-6 < 2x < 10\\\\-6+9 < 2x+9 < 10+9\\\\\\\boxed{3 < 2x+9 < 19}[/tex]