1. The problem statement, all variables and given/known data "A metal wire has a resistance of 10 ohms at a temperature of 20 degrees C. If the same wire has a resistance of 10.55 ohms at 90 degrees C, what is the resistance of this same wire when its temperature is -20 degrees C?" 2. Relevant equations I am not exactly having trouble solving this problem. It's just that my teacher realized after she wrote the problem that she never taught us the relationship between heat and electrical resistivity. Therefore she gave us the problem as extra credit and told us to find out how to solve it on our own. So all I am really looking for is an equation. I would like to do the calculations myself, but if someone could point me in the right direction, it would be greatly appreciated.