so, he earns "x", which is the 100%, now, we know 140 is 2.5%, so, what is "x"?
well [tex]\bf \begin{array}{ccllll}
amount&\%\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
x&100\\
140&2.5
\end{array}\implies \cfrac{x}{140}=\cfrac{100}{2.5}[/tex]
solve for "x"
