the problem says:

In a right triangle, if one leg (adjacent to 90o) is 3cm, which is increasing

at the speed of 2cm/second; and another leg is 4cm, which is decreasing at

the speed of 2cm/second. How fast is the hypotenuse changing at this time?

this is what i came up with https://www.dropbox.com/s/eyaw81bvue...2001.54.53.jpg

i know for a fact i messed up somewhere towards the end...can someone please guide me in the right direction? thanks!