4 . [T] If two electrical resistors are connected in parallel, the total resistance (measuredin ohms, denoted by the Greek capital letter omega, ) is given by the equation R=R1+R2. If R1 is increasing at a rate of 0.5/min and R2 decreases at a rate of 1.1/min, at what rate does the total resistance change when R1=20 and R2=50?