The voltage, V, (in volts) across a circuit is given by Ohm's law: V = IR, where I is the current (in amps) flowing through the circuit and R is the resistance (in ohms). If we place two circuits, with resistance R1 and R2, in parallel, then their combined resistance, R, is given by 1/R=1/R1+1/R2. Suppose the current is 2 amps and increasing at 10-2 amp/sec and R1 is 4 ohms and increasing at 0.5 ohm/sec, while R2 is 5 ohms and decreasing at 0.1 ohm/sec. Calculate the rate at which the voltage is changing.