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. What is the length of the rectangle?  Choose the correct choice from the following choices.
A) 20cm	B) 40cm	C) 30cm	D) 60cm	E) 50cm
Let breadth =x cm   Then, length =2x cm   Area =x×2x=2x2 sq.cm.   New length =(2x−5) cm   New breadth =(x+5) cm   New area =(2x−5)(x+5) sq.cm.   Given that, new area = initial area +75 sq.cm.   ⇒(2x−5)(x+5)=2x2+75⇒2x2+10x−5x−25=2x2+75⇒5x−25=75⇒5x=75+25= 
<gadget id="calculator">75+25</gadget>
<output>100</output>
100⇒x=1005=20 cm   Length =2x=2×20=40cm   Answer is 40cm.
<result>B</result>
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. What is the length of the rectangle?