she earned $192 in commission, and we know that's 8%, so how much will it be for say the 100%, the whole total of the sales?
[tex]\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 192&8\\ x&100 \end{array}\implies \cfrac{192}{x}=\cfrac{8}{100}\implies \cfrac{192}{x}=\cfrac{2}{25} \\\\\\ 4800=2x\implies \cfrac{4800}{2}=x\implies 2400=x[/tex]