I would enter formulas and square/rectangle requirements into a spreadsheet, add more formulas and divide by 36. Gets closer numbers than EQ and it provides the cutting plan. I love spreadsheets and use them for many things.
Here is a small example:
fabric needed length how many widths
White 2.5 8 5 42/8 100/5 =?? 27 inches or 1/3 yd and so on for each color and shape, then make your spreadsheet add them up and convert to yardage.
I didn't do any real math here, but you just need to remember "cuts across" and ??widths are up and will give the ydg