Let $x$ be her weekly salary. She spends $\frac58x$ on rent; the remainder is what’s left, so the remainder is $x-\frac58x=\frac38x$. She spends $\frac13$ of that, or $\frac13\cdot\frac38x=\frac18x$, on food; that leaves $\frac38x-\frac18x=\frac14x$ for other expenses. Can you finish it now?