A boat has a speed of 15 mph in calm water. It takes the boat 3 hours to travel upstream but only 2 hours to travel the same distance downstream. Which equation can be used to find c, the speed of the current in miles per hour?

Upstream, the current slows the boat, so its speed is 15 − c mph. In 3 hours, it travels 3(15 − c) miles. Downstream, the current adds to the boat’s speed, giving 15 + c mph; in 2 hours, it travels 2(15 + c) miles. Since both trips cover the same distance, set these expressions equal: 3(15 − c) = 2(15 + c), which is choice A.

AI-written and checked against the verified answer.