Simultaneous equations concepts -- distance, rate and time

If you travel 30 miles per hour for 4 hours, how far do you go? A little common sense will tell you that the answer is 120 miles.

This relationship is captured in the following equation:

$d=rt$ where...

• $d$ is distance traveled (sometimes the letter x is used instead, for position)
• $r$ is the rate, or speed (sometimes the letter v is used, for velocity)
• $t$ is the time

This is presented here because it forms the basis for many common simultaneous equations problems.