Question

b is decreased by 40% and decreased again by 40% . What is the result ?

Answer 1

Answer:Let b = 100

First decrease = 40% = 40

= 100 - 40 = 60

Now it's again decreased by 40% = 40/100 × 60 = 24.

Step-by-step explanation:

Answer 2

Answer:

Required result is $\frac{9b}{25}$

Step-by-step explanation:

Given,b is decreased by 40% and decreased again by 40%.

We want to find final result.

We know,

x% of y

$= \frac{x}{100} \times y$

And x% increase from y $\frac{100 + x}{100} \times y$

and x% decrease from y $\frac{100 - x}{100} \times y$

Here first b decreased by 40%

$= \frac{100 - 40}{100} \times b \\ = \frac{60}{100} \times b \\ = \frac{3}{5} \times b$

Again

$\frac{3b}{5}$ decreased by 40%

So,

$\frac{3b}{5} \times \frac{100 - 40}{100} \\ = \frac{3b}{5} \times \frac{60}{100} \\ = \frac{3b}{5} \times \frac{3}{5} \\ = \frac{9b}{25}$

This is a problem of Algebra.

Some important Algebra formulas.

(a + b)² = a² + 2ab + b²

(a − b)² = a² − 2ab − b²

(a + b)³ = a³ + 3a²b + 3ab² + b³

(a - b)³ = a³ - 3a²b + 3ab² - b³

a³ + b³ = (a + b)³ − 3ab(a + b)

a³ - b³ = (a -b)³ + 3ab(a - b)

a² − b² = (a + b)(a − b)

a² + b² = (a + b)² − 2ab

a² + b² = (a − b)² + 2ab

a³ − b³ = (a − b)(a² + ab + b²)

a³ + b³ = (a + b)(a² − ab + b²)

Know more about Algebra,

1) https://brainly.in/question/13024124

2) https://brainly.in/question/1169549