To solve the given literal equation for $y$:

$2x - 4y = 20$

Follow these steps:

1. Isolate the term involving $y$: $-4y = 20 - 2x$ This was achieved by subtracting $2x$ from both sides of the equation.

2. Solve for $y$: $y = \frac{20 - 2x}{-4}$

3. Simplify the expression: Break the fraction into two terms: $y = \frac{20}{-4} - \frac{2x}{-4}$ Simplifying each term: $y = -5 + \frac{x}{2}$

Thus, the solution is: $y = \frac{x}{2} - 5$

Would you like more details on any step? Here are some related questions for practice:

1. What would the equation look like if solved for $x$ instead of $y$?
2. How would the graph of the equation $y = \frac{x}{2} - 5$ look?
3. What is the slope and y-intercept of the line given by the equation $y = \frac{x}{2} - 5$?
4. How would you solve this equation if it involved a more complicated fraction?
5. What happens if the right-hand side of the original equation changes to a different constant, such as 30?

Tip: Always try to simplify fractions early to make your calculations easier!