Question

One year, the population of a city was 110,000. Several years later it was 102,300. Find the percent decrease.

Answer 1

the decrease was clearly 110000 - 102300 = 7700.

now, if we take 110,000(origin amount) as the 100%, what is 7700 off of it as a percentage?

`\begin{array}{ccll} amount&\%\\ \cline{1-2} 110000 & 100\\ 7700& x \end{array} \implies \cfrac{110000}{7700}~~=~~\cfrac{100}{x} \\\\\\ \cfrac{ 100 }{ 7 } ~~=~~ \cfrac{ 100 }{ x }\implies 100x=700\implies x=\cfrac{700}{100}\implies x=7`