Hello folks, glad I found this site. I wonder if anyone could help me with my son's math problem, I'm kind of a retard when it comes to this stuff. Say I have a group of ten batteries, their are 6volt and 12volt batteries with the total sum of 84 volts, how do I write the equation? I know we need 4 12v and 6 6v batteries for a total 10 batteries and 84volts, but not sure how to write it. Thanks for any help, and glad to be here. Scott