Question

plz solve it fast...number 17 18​

Answer 1

Answer:

Ans 17) Let the number be 100 if it increases by 20% the number will become 120 and now if 120 is decreased by 20% it would become 96.

So in all the number is decreased by 4%

Ans 18) Let the number be 100 if it decreases 40% it would become 60 and now if it increases 60% it would become 96.

So in all the number is decreased by 4%.

I chose the number 100 in both the question so that it is easy to calculate you can use other numbers also.

Mark as brainliest pls

Answer 2

Answer:

let the number be x

first increase 20%

$new \: number \: = x + 20\% \: of \: x \\ \\ = x + \frac{20 \times x}{100} \\ \\ = x + 0.2x \\ \\ = 1.2x$

Now it decreased by 20%

$number \: \: after \: \: decresed \: \: by \: \: 20\% \\ \\ = 1.2x \: \: - \: \: 20\% \: of \: 1.2x \\ \\ = 1.2x - \frac{20 \times 1.2x}{100} \\ \\ = 1.2x - 0.24x \\ \\ = 0.96x$

Now whole number we get 0.96x which is decreased from original number

$decrease \: = \: x - 0.96x \\ = 0.04x$

Now decrease percent

$d\% = \frac{0.04x}{x} \times 100 \\ = 4\%$

Hence Number is decreased by 4%