Question

If the cost of sending a first class letter is 45 cents four the first ounce and 20 cents for each additional ounce or fraction thereof,write a piecewise function rule modeling the cost of a letter that weighs up to 3 oz

Answer 1

We will have the following piecewise function represent the problem:

$f(x)=\begin{cases}20x+45\colon x>1\land x<3 \\ 45\colon x=1\end{cases}$