Set 1: Linear Equations (Advanced)

Choice C is correct. Choice C is the correct answer. 1. Speeds: Down = $20 /2 = 10$, Up = $20 /5 = 4$. 2. Equations: $b + c = 10$, $b - c = 4$. 3. Subtract: $2c = 6 \rightarrow c = 3$. Choice A is incorrect because this is the boat speed. Choice B is incorrect because it results from an error in the solution process. Choice B is incorrect because it results from an error in the solution process.