[masraum]

I assume you're in Calc and working with derivatives and related rates?

< EDIT >BLAH, BLAH, BLAH. THERE WAS A TYPO IN MY FIRST ANSWER. GIMME A MINUTE TO REWRITE IT.< /EDIT >

A great online resource for math, especially college (Algebra, Calc I/II/III and DE) is "Paul's online math notes" (apparently a professor at Lamar Univ in Texas)

Here's a link to his Calc I notes.
http://tutorial.math.lamar.edu/Classes/CalcI/CalcI.aspx

Here's his main site.
http://tutorial.math.lamar.edu/