How can you solve ROI?

by jail breaking it

I guess you mean simultaneous equations. There are three methods of solving these equations: graphing if the variables are x and y (though this is only an approximate method and should be avoided...

It´s a term often used in retail business which stands for "return on investment".

it is 10

A carpenter wants to put four shelves on an 8-foot wall so that the five spaces created decrease by 6 inches as we move up the wall. If the thickness of each shelf is 3/4 inch, how far will the...