The length of a rectangular blackboard is 8 cm more than its breadth .If its length is increased by 7 cm and breadth is decreased by 4 cm ,its area remains unchanged .Find the length and breadth of the rectangular blackboard?
Answers
Answered by
1
Answer:
L= 28
B= 20
Step-by-step explanation:
L= 8+B
L'= (8+B)+7 = 15+B
B'= B-4
Area is same
L x B = L' x B'
(8+B)B = (15+B) (B-4)
3B =60
B=20
L=8 +20
Answered by
4
Answer:
Let the length be L and breadth be B
Given, L=8+B
Area of the board, L×B=(8+B)×B
Given, If its length is increased by 7 cm and breadth is decreased by 4 cm, its area remains unchanged.
⇒(L+7)(B−4)=L×B
But L=8+B
⇒(8+B+7)(B−4)=(8+B)×B
⇒(15+B)(B−4)=(8+B)×B
⇒15B−60+B
2
−4B=8B+B
2
3B=60
B=20 cm
So, Length =20+8=28 cm
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