Question

A blanket, when bleached, lost 20% of its length and 15% of its breadth. what is the percentage decrease in area?

Answer 1

Answer:

Let % be x .

Decrease in Length = 20

Decrease in Breadth = 15

Step-by-step explanation:

so eqn = 20x+15x =35x

Answer 2

Answer:

The percentage decrease in area is 32%.

Step-by-step explanation:

Given,a blanket, when bleached, lost 20% of its length and 15% of its breadth.

Let, length of the blanket be x unit and breadth of the blanket be y unit.

We know, area of a rectangle = length × breath

Here length is x unit and breadth is y unit.

So,

$area=(x \times y) \\ = xy \:square \:\:unit$

Now after bleaching,lost 20% of its length and 15% of its breadth.

So,now length is

$(100 - 20)\% \: of \: x = 80\% \: \: of \: x \\ = \frac{80}{100} \times x \\ = \frac{4x}{5} \: \: unit$

and breadth is

$(100 - 15)\% \: \: of \: y = 85\% \: of \: y \\ = \frac{85}{100} \times y \\ = \frac{17y}{20} \: unit$

Now,

$area =\frac{4x}{5} \times \frac{17y}{20} \\ = \frac{x}{5} \times \frac{17y}{5} \\ = \frac{17xy}{25} \: square \:\:unit \:$

Area decrease

$= xy - \frac{17xy}{25} \\ = \frac{25xy - 17xy}{25} \\ = \frac{8xy}{25}\: square \:\:unit$

We know xy square unit means 100%

By Unitary method,

1 square unit means $\frac{100}{xy} \%$

and $\frac{8xy}{25}$square unit means

$\frac{100}{xy} \times \frac{8xy}{25 } \\ = 4 \times 8 \\ = 32\%$

Some more conceptual maths about rectangle:

1) https://brainly.in/question/18298929

2) https://brainly.in/question/3015557