Hi, I'm pretty new to the world of electronics, and I'm attempting an small project that I need some help upon.

1. If there are three wires carrying input voltages, how can i make it so that the output voltage equal to the sum of the three input voltages? Please see image below.

2. If there are two wires carrying two input voltages, how can I make it so that the motor turns one way when Vx>Vy then turn the other way when Vy>Vx? Vx and Vy are voltage outputs from a colorimeter. Please see image below.
http://server6.uploadit.org/files/battlestar-motor.jpg


Thank you very much [Linked Image]