
a)
at 0hours, the plane is 2700miles away from its destination, so the plane is on a city which is 2700miles from its destination and the pilots are sipping coffee
b)

![\bf \begin{array}{ccllll} hours[x]&miles[f(x)]\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 0&2700\\ \boxed{1}&\boxed{2160}\\ 2&1620\\ 3&1080\\ \boxed{4}&\boxed{540} \end{array} \qquad \begin{array}{llll} \begin{cases} x_1=1\\ x_2=4 \end{cases}\implies \cfrac{f(4)-f(1)}{4-1}\\\\\\ \cfrac{2160-540}{4-1} \end{array}](https://img.qammunity.org/2018/formulas/mathematics/college/zqsw3pqzt8fb9scazgutfk2e121f4xykbs.png)
c)
well, notice from b), the distance is dropping a constant value, 1 more hour, and the plane is at its destination, so the domain will be from [0, 5]