Question

What percent of the current number of states had joined the United States by the year 1863?

Answer 1

we know the 100% is 50 today, by 1863 there were 35, so what is 35 in percentage off 50?

$\begin{array}{ccll} amount&\%\\ \cline{1-2} 50&100\\ 35&x \end{array}\implies \cfrac{50}{35}=\cfrac{100}{x}\implies \cfrac{10}{7}=\cfrac{100}{x} \\\\\\ 10x=700\implies x=\cfrac{700}{10}\implies x=70$