<PRE><B>Question 855669</B>
Perimeter = sum of all the 4 sides. A rectangle has 2 equal sides of length, and
2 equal sides of width.
So the perimeter = 2*(Length + Width) 
= 2*length + 2*width = 2*x + 2*width = 300 (given that length is x)
Simplifying (dividing both sides of the equation by 2)

x + width = 150

Therefore, width = 150 - x

Hope this helps :)
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