Question

Ross had 85 papers to grade from his students. He has graded 60 of them. Approximately what percentage of papers does he have left to grade?

Answer 1

well, our origin amount will be 80, so 80 is the 100% or all papers, now, she has graded 60, so what's leftover is 20, what's 20 off of it in percentage?

`\begin{array}{ccll} amount&\%\\ \cline{1-2} 80 & 100\\ 20& x \end{array} \implies \cfrac{80}{20}~~=~~\cfrac{100}{x} \\\\\\ 4 ~~=~~ \cfrac{ 100 }{ x }\implies x=\cfrac{100}{4}\implies x=25`