As a fleet manager for a logistics company, you frequently use the uniform motion strategy to schedule and track deliveries. When setting up an equation to find the travel time for two delivery vans that depart from the same depot at the same time and travel in opposite directions, which mathematical relationship must you recall to correctly represent their total separation?

As a dispatcher for a regional delivery service, you are tracking two drivers, Pierre and Monique, who leave the warehouse at the same time. Pierre travels North at 75 mph and Monique travels South at 68 mph. You need to determine how many hours ($t$) it will take for them to be exactly 429 miles apart. Arrange the steps of the uniform motion problem-solving strategy in the correct order to reach the solution.

When using the uniform motion strategy to find the time it takes for two vehicles departing from the same point and traveling in opposite directions to reach a specific total separation, the equation is set up by adding their individual distances together and setting that sum equal to the total distance apart.

A logistics coordinator is tracking two field representatives, Pierre and Monique, who depart from a regional distribution center at the same time and travel in opposite directions. Pierre drives North at ${}75$ mph and Monique drives South at ${}68$ mph. To determine how long it will take for them to be ${}429$ miles apart, the coordinator uses the equation ${}75t + 68t = 429$. Match each mathematical component of this equation with the physical representation it identifies in this logistics scenario.

In the tracking model ${}75t + 68t = 429$, which calculates the travel time for two vehicles moving in opposite directions, the variable $t$ represents the time elapsed. Given that the vehicle speeds are provided in miles per hour, the specific unit of measurement for $t$ must be ____.