Question 1126666
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P = perimeter of rectangle
L = length = 15
W = width = y
P = 2*(L+W)
P = 2*(15+y)
P = 30+2y


Since the "perimeter is more than 50" we know that P > 50 or 50 < P. 
At the same time we're told that the perimeter is "less than 70", so P < 70.
Combine 50 < P and P < 70 to get 50 < P < 70


50 < P < 70
50 < 30+2y < 70 <font color=blue>Replace P with 30+2y</font>
50-30 < 30+2y-30 < 70-30 <font color=blue>subtract 30 from all sides</font>
20 < 2y < 40
20/2 < 2y/2 < 40/2 <font color=blue>divide all sides by 2</font>
10 < y < 20


<font color=red> Answer: Choice B. 10 < y < 20 </font>
This means that y can be anything between 10 and 20 as long as it's not 10, and it's not 20 either. 
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