a)
150 ÷ 25 = 6
meaning each ball cost him 6 bucks, and then he sells the for 8 or namely 2 bucks extra.
if we take 6 to be the 100%, what is 2 off of it percentage?
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 6&100\\ 2&x \end{array}\implies \cfrac{6}{2}=\cfrac{100}{x}\implies 3=\cfrac{100}{x} \\\\\\ 3x=100\implies x=\cfrac{100}{3}\implies x=33.\overline{3}[/tex]
b)
well, we know each cost him 6 bucks, if he sells them for 5, he's losing 1 buck, so if take 6 to be the 100, what is 1 off of it in percentage?
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 6&100\\ 1&x \end{array}\implies \cfrac{6}{1}=\cfrac{100}{x}\implies 6=\cfrac{100}{x} \\\\\\ 6x=100\implies x=\cfrac{100}{6}\implies x=16.\overline{6}[/tex]
