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 [pmath]Distance = rate * time[/pmath]. Here is an example problem:

A man can row at [pmath]6 km/h [/pmath]in still water. The speed of the river he now rows in is [pmath]4 km/h[/pmath]. How long will it take him to row upstream [pmath]30 km[/pmath]?

Using the formula [pmath]distance= rate*time [/pmath]we will rearrange it to solve for time. Now, [pmath]distance/rate= time[/pmath]. Our distance is a 30 km and our rate is his speed in stillwater minus the current speed. So, [pmath](30km)/(6-4 km/hr)= time[/pmath]. Simplifying, [pmath](30km)/(2km/hr)= time[/pmath]. Finally, time equals 15 hours.

Oar propelled ship. Abraham Willaerts (circa 1603–1669).

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