Question

the price of a 70 inch tv was reduced from 800$ to 600$ on black friday by what percentage was the tv reduced

Answer 1

well, from 800 to 600 is 200 bucks.

if we take 800 to be the 100%, what is 200 off of it in percentage?

$\begin{array}{ccll} amount&\%\\ \cline{1-2} 800 & 100\\ 200& x \end{array} \implies \cfrac{800}{200}=\cfrac{100}{x}\implies 4=\cfrac{100}{x} \\\\\\ 4x=100\implies x=\cfrac{100}{4}\implies x=25$