before the raise, Yara was making "x", which is 100% of her salary,
now, later on she got a 6% of that "x" in increased salary, and she's
making 3,120, so 100% + 6% added, is 3,120
thus [tex]\bf \begin{array}{ccllll}
amount&\%\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
x&100\\
3,120&100+6
\end{array}\implies \cfrac{x}{3,120}=\cfrac{100}{100+6}[/tex]
solve for "x"
