If two resistors with resistances R1 and R2 are connected in parallel, , then the total resistance R, measured in ohms (Ω), is given by

1/R = 1/R1 + 1/R2

If R1 and R2 are increasing at rates of 0.3 Ω/s and 0.2 Ω/s, respectively, how fast is R changing when R1 = 60 Ω and R2 = 70 Ω?