Final answer:
The cost in dollars for x number of rides, if each ride costs $20, can be found using the equation c = 20x.
Step-by-step explanation:
The correct equation to calculate the cost in dollars for x number of rides, if each ride costs $20, is option 2) c = 20x.
This equation represents a linear relationship between the number of rides (x) and the cost (c), with a constant rate of $20 per ride. For example, if x = 3, the cost would be 20 * 3 = $60.
Therefore, the cost in dollars for x number of rides can be found by multiplying the number of rides (x) by the cost per ride ($20).