Question

Two cars started at the same time, from the same point, driving along the same road. The rate of the first car is 50 mph and the rate of the second car is 60 mph. How long will it take for the distance between the two cars to be 30 miles?
Show Work.

Answer 1

See my attached picture.
Remember that distance is speed*time, d = s*t.
$d_{1} = s_{1}t = 50 \frac{mi}{h} * t \\ d_{2} = s_{2}t = 30\frac{mi}{h} * t$

The distance for both cars total is 30. As a formula, this is
$d_{1} + d_{2} = 30$.

Putting the formulas together,
$50t + 30t =30 \\ 80t = 30 \\ t = 3/8$
The time it takes is 3/8 hours.