SOLUTION: Kina solved -15q<135 by adding 15 to each side of the inequality. What mistake did she make? B. kina's solution was q<150. She checked her work by substituting 150 for q in the or

Question 26350: Kina solved -15q<135 by adding 15 to each side of the inequality. What mistake did she make?
B. kina's solution was q<150. She checked her work by substituting 150 for q in the original inequality. Why didn�t her check let her know that she had made a mistake?

Found 2 solutions by queenofit, Earlsdon:
Answer by queenofit(120) (Show Source): You can put this solution on YOUR website!
First of all, Kina should not have added 15 to anything, she would have had to divided both sides of the equation by -15. The -15 is multiplied to the q not subracted.
when she checked her answer it gave her a number that was less than 135 so she thought that she was correct, but she was not.
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
First, Kina tried to add un-like terms (-15q+15) does not equal q, it equals (-15q+15). When she used 150 to check her solution, it would appear to have checked out because she would have ended up with: -2250<135 and this is true.
What Kina should have done is divide both sides of the inequality by -15 and, in doing this, she also should have reversed the order of the inequality.
Divide both sides by -15 and reverse the order of the inequality.

To check her solution, Kina should try a number that is greater than -9 because her solution is the set of all numbers greater than -9.
Try -5:

It checks!
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