Choice C is the correct answer. Let's check if one equation is a multiple of the other.

Step 1: Divide the first equation by 5: $\frac{15x - 20y}{5} = \frac{25}{5}$$3x - 4y = 5$

This is exactly the second equation!

Conclusion: Infinitely many solutions (identical lines)

💡 Strategic Tip: Always look for common factors in all terms—factoring simplifies comparison.

Choice A is incorrect because no solution requires parallel lines with different constants.

Choice B is incorrect because one solution requires different slopes.

Choice D is incorrect because simplification always reveals the relationship.