First, distribute 2 to the (x+3) to get:
21 = 2x+6
subtract 6 from both sides to get:
15 = 2x
Finally, we divide both sides by 2 to simplify x to:
x = 7.5 (OR) x =

(Just so you know, if you pick a brainliest answer, both you and the person who got the brainliest answer get some points.
<h3>Answer:</h3>
room 3 or 4
<h3>Explanation:</h3>
We assume the inequalities tell the rooms that were checked and found empty.
The solution to 3) is ...
... 2x + 3 > 11
... 2x > 8 . . . . . subtract 3
... x > 4 . . . . . . .divide by 2
The solution to 4) is ...
... -3x > -9
... x < 3 . . . . . . divide by -3
Thus, rooms greater than 4 and less than 3 were found empty. Rooms 3 and 4 were not checked, so either one could hold Nessie.
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The other inequalities have solutions that are already covered by the solutions to these.
1) x < -1 . . . . after subtacting 4
2) x > 5 . . . . after multiplying by 5
I think it is 0 because I googled it.