I'm having trouble with this basic math question. Any hints?
Given a graph with lines $x=y$ and $x+3y=4$. Consider the triangle formed by these two lines and $y=0$.
When $y$ is increasing from $0$ to $1$, how is the length of $y$ (slice inside the triangle) decrease? As in what function does that describe? For example, the slice length is $4$ when $y=0$ and $0$ when $y=1$.