In Algebra 2, we may be asked to look at rates. Often these come in the form of speed and distance questions. The general formula for this type of problem is . Here is an example problem:
A man can row at in still water. The speed of the river he now rows in is . How long will it take him to row upstream ?
Using the formula we will rearrange it to solve for time. Now, . Our distance is a 30 km and our rate is his speed in stillwater minus the current speed. So, . Simplifying, . Finally, time equals 15 hours.