Answer:
![0 \le t < \infty](https://img.qammunity.org/2022/formulas/mathematics/high-school/ymdb47yfq26p5lmdlk8i8dxundzpy9lni5.png)
Explanation:
Given
![c(t) = 3t](https://img.qammunity.org/2022/formulas/mathematics/high-school/oiddjud3ezgmadr4lemz5i8wx221zqpa0m.png)
Required
The domain
From the question, we understand that t represents number of yards/packages (depending on the store)
This means that:
---- the start value
--- the end value
Rewrite
as
![0 \le t](https://img.qammunity.org/2022/formulas/mathematics/college/4z6nv74vy5a94gm39kxigz6mx3tu1mwvuc.png)
So, we have:
and
![t < \infty](https://img.qammunity.org/2022/formulas/mathematics/high-school/6q9qw4bp90a8acp5comsrx7ulb8shxl0h2.png)
Hence, the domain is:
![0 \le t < \infty](https://img.qammunity.org/2022/formulas/mathematics/high-school/ymdb47yfq26p5lmdlk8i8dxundzpy9lni5.png)