What is the perimitter of the original rectangle in cm is?

Question

if we increase the length and the width of rectangle by 10 cm each. the area of the rectangle will increase by 300 cm^2? The permitter of original rectangle in Cm is?

Answer 1

Let x = original length and y = original width

Then, (x+10)(y+10) = xy + 300

So, xy + 10x + 10y + 100 = xy + 300

10x + 10y = 200

Original perimeter = 2x + 2y = 40 cm

Answer 2

Let x & y be the length & the width of the original rectangle respectively, then:

The area of the original rectangle = xy

The perimeter of the original rectangle = 2x + 2y

Now the new rectangle's area:

(x + 10)(y + 10) = xy + 300

xy + 10x + 10y + 100 = xy + 300

10x + 10 = 200 => divide both sides by 5:

2x + 2y = 40 cm

thus:

Perimeter of the original rectangle = 40 cm