Question 1058494: Three times a number is greater than or equal to 12 and less than 21
Answer by solve_for_x(190)   (Show Source):
You can put this solution on YOUR website! Let x represent the unknown number.
Three times that number is then represented as 3x.
Since this value must be "greater than or equal to 12, and less than 21",
you can write:
12 ≤ 3x < 21
Dividing through by 3 leaves:
12 / 3 ≤ 3x / 3 < 21 / 3
4 ≤ x < 7
Solution: The number must be greater than or equal to 4, and less than 7.
In interval notation, the solution is [4, 7).
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