Statistics homework help

I want to know the answers and how to calculate it! Thank you so much!Attachment 1Attachment 2RTR2R3AVIn the diagram above :R1 = 1 0R2 = 3 0R3 = 2 0and the voltage supplied by the power supply is V = 15 VWhat single resistor could replace R. I and R2, resulting in the circuit having the same total resistance ?!V Q