If you copy a document on a​ machine, you should get a similar copy. Suppose you want to reduce a document to of its original size and you first reduce it by ​%. By what percent do you need to reduce the copy to obtain the desirable​ size?

the numbers are missing, so I looked for a similar question:

If you copy a document on a machine, you should get a similar copy. suppose you want to reduce a document to 1/6 of its original size, and first reduce it by 25%. By what percent do you need to reduce the copy to obtain the desirable size?

You want the copy to be 1/6 of the original size = 16.67%

Since you first reduced the copy by 25%, the image is now 75% of its original size. In order to finally obtain a copy that is 16.67% of the original size, you must reduce this second copy by 1 - (16.67%/75%) = 77.78% ≈ 78%.

we can check our

size of second copy x (1 - reduction)

0.75 x (1 - 0.7778) = 0.1667

true

explanation: