As a logistics coordinator for a river freight company, you are creating a rate-time-distance table to plan delivery routes. If the variable $r$ represents the speed of your delivery boat in still water and the variable $c$ represents the speed of the river's current, which mathematical expression correctly represents the boat's rate of travel when it is moving upstream (against the current)?

A logistics coordinator for a ferry service is standardizing the workflow for calculating vessel performance on tidal rivers. When a boat travels different distances upstream and downstream in the same amount of time, a specific algebraic strategy is used to find the boat's speed in still water. Arrange the following steps in the correct order to set up and solve this uniform motion application.

As a logistics manager for a river transport company, you are standardizing the formulas used by your route planners for boat speed calculations. Match each navigational concept with the correct mathematical expression, where $r$ represents the vessel's speed in still water, $c$ represents the speed of the river current, $d$ represents distance, and $t$ represents time.

Maritime Logistics: Vessel Transit Analysis

A boat operator notes that a vessel travels different distances upstream and downstream in equal time. To calculate the boat's speed, the operator should set up an algebraic equation by setting the two distances equal to each other.

As a logistics manager for a river transport company, you are standardizing the formulas used by route planners. If $r$ represents a vessel's speed in still water and $c$ represents the speed of the river's current, the algebraic expression used for the vessel's total rate of travel when it is moving downstream (with the current) is ____.