Graphing Piecewise and Step Functions

Let $y=f(x)$ and $x$ be the cost and weight, respectively. We are told that first-class postage was $\$0.42$ for up to $\text{one ounce}.$ Remember that up to means less than or equal to. In this case, the rule and domain for the first step can be written as shown below. $$\begin{array}{c}f(x)=0.42,\text{for }0<x\le 1\end{array}$$ Since the cost increases by $\$0.17$ for each additional ounce, we can write the rule of the next steps by adding $0.17$ to the first step until the domain reaches to $3.5.$ $$\begin{array}{c}f(x)=\{\begin{array}{l}0.42,\text{for }0<x\le 1\\ 0.59,\text{for }1<x\le 2\\ 0.76,\text{for }2<x\le 3\\ 0.93,\text{for }3<x\le 3.5\end{array}\end{array}$$ The function we wrote pairs every number in each interval with a single value. Therefore, it is a step function. Each piece of its graph will be a horizontal line that is missing its left endpoint. We will show the left endpoints using open points and the right endpoints using closed points. Let's graph it!