Question 657326: Solve
-45 < -5x - 15 < 45
Answer by Shana-D77(132)   (Show Source):
You can put this solution on YOUR website! In equations, there are 2 "sides" on either side of the = sign. In your problem, there are 3 "sides", so we add, subtract, multiply, divide all 3 sides:
-45 < -5x - 15 < 45
-30 < -5x < 60 (added 15 to all 3 "sides")
Now, we have to divide by a negative, so we need to make all the < turn to >. If you want to know why this is, look below.
-30 < -5x < 60
6 > x > -12 (divided all 3 "sides" by -5)
-12 < x < 6 (flipped the whole thing around because it's nice to read from the smallest number)
So why do we flip the < sign? Here's an example:
5 < 10 (true)
Let's arbitrarily divide both sides by -1:
-5 < -10 (no longer true!)
So, when we divide by negatives, we must flip the inequality signs:
-5 > -10
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