c) \( x-5 y=20 \)

This equation represents a linear relationship between \( x \) and \( y \). If you solve for \( y \), you'll find that it's in the form \( y = \frac{1}{5}x - 4 \). This means that for every 5 units you increase \( x \), \( y \) increases by 1 unit – a classic signature of linear equations. In the real world, such linear equations can model various situations! For example, if \( x \) represents the number of hours worked and \( y \) represents the earnings in hundreds of dollars, this can help you quickly see how potential income changes as you work more hours. Just imagine plotting this on a graph; the straight line you would draw visually showcases that steady relationship!