in a business would like to make a chart based on accumulated Earnings &
Profit/Loss for year to date, perhaps movable showing our break even point
and by moving chart to a another earnings figure what profit we should make.

For example put in earnings for YTD Profit/Loss YTD then I can move the
earnings part of the chart to show what our profit would be for a given
earnings figure.

Alternatively

If For example if we earn $200 for year so far and profit is $0 but any
amount over that is 18% profit so I can move chart line to say $240 and it
will say what profit I will make.

Hope I make sense with these two questions