Q:
      
      
         
            
The length of a rectangle is twice its breadth. If its length is decreased by 5 cm and breadth is increased by 5 cm, the area of the rectangle is increased by 75 sq.cm. Find the length of the rectangle?
         
       
      
      
      
          
      
      
          Answer & Explanation
         Answer: B) 20cm         
         
Explanation: Let the breadth of the given rectangle be x then length is 2x. 
 thus area of the given rect is 
 
 
 
after dec 5cm from length and inc 5cm breadth , new lenght becomes 2x-5 and breadth is x+5.thus new area =(2x-5)(x+5)=
since new area is 75 units greater than original area thus 
 5x=75+25 
 5x=100 
 therefore x=20 
 hence length of the rectangle is 40 cm.
       
      
      
      
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