Set 15: Systems of Equations (Intermediate)

Choice B is correct. Choice B is the correct answer. Let $c$ = canoe speed in still water and $r$ = river current speed. System: $\begin{cases} (c + r) \cdot 2 = 24 \\ (c - r) \cdot 4 = 24 \end{cases}$ Step 1: Simplify: $\begin{cases} c + r = 12 \\ c - r = 6 \end{cases}$ Step 2: Add equations: $$$2c = 18c = 9$$ Solution: Canoe speed is 9 mph in still water Verification: Downstream: (9+3) \times 2 = 24$✓, Upstream:$(9-3) \times 4 = 24$ ✓ Strategic Tip: Current helps downstream, opposes upstream. Other choices fail verification.