Question

The area of a rectangle gets reduced by 80 sq.units, if its length is reduced by 5 times and breadth

is increased by 2 units. If we increase the length by 10 units and decrease the breadth by 5 units

the area will increased by 50 sq.units. Find the length and breadth of the rectangle.​

Answer 1

Step-by-step explanation:

Let the length and breadth of the rectangle be a,b units respectively.

Then the area will be ab square units.

Now if the length of the rectangle is reduced by 5 units and breadth is increased by 2 units then new length and breadth will be (a−5) units and (b+2) units.

Then new area will be (a−5)(b+2).

Then according to the problem,

(a−5)(b+2)−ab=−80

or, 2a−5b=−70.......(1).

Now if length of the rectangle is increased by 10 units and breadth is decreased by 5 units then new length and breadth will be (a+10) units and (b−5) units.

Then new area will be (a+10)(b−5).

Then according to the problem,

(a+10)(b−5)−ab=50

or, 10b−5a=100

or, 2b−a=20

or, 4b−2a=40......(2).

Now adding (1) and (2) we get

−b=−30

or, b=30.

Putting the value of b in (1) we get, a=40.

Now a+b=40+30=70.