Percent problems

By how many percent should we shorten the edge of a cube so that its surface area is decreased by \( 19\% \)?

The number of permanent residents of a city has decreased by \( 10\% \) per year in the last three years. How many residents did the city have three years ago, if we know that the last year the population was \(972\)?

Find the number by \( 2.5{\small{{}^\text{o}\mkern-5mu/\mkern-3mu_\text{oo}}} \) greater than \( 800 \).

There are \(14\) right-handed and \(18\) left-handed children among the children attending the ceramic group. Find the difference between percentages of right-handers and left-handers in the group. (Round the result to one decimal place.)