Ok two resistors R1 and R2 are connected parallel.

Total resistance is given by $\displaystyle R^-1 = R1^-1 + R2^-1$

R1 is 80 ohms & increases at 0.3 ohms per sec

R2 is 100 ohms & increases at 0.2 ohms per sec

so the question is now, "how fast is R changing at that time?"

not sure how to go about this question. any help much appreciated