I think I need a graphing calculator of some kind.

I want a calculator or a formla for a spread sheet or just a quick way to work out a math problem.

If 30 units = 500 and 300 units = 1500

From this a line on a graph could be drawn that would then tell me the value of any number of units.

what would say 80 units = ?

Maybe I could have explained this better. I hope it makes sense.

Any ideas anyone?

Thanks

MIke