I made a simple excel graph with 2 lines showing the cumulative costs of a gaz car costs and an electric car cumulative costs.
On the horizontal you see the years (2016 2017 2018 2019 2020...)
And on the vertical line you see the cumulative costs ( 10,000 20,000 30,000 ....)
In this exemple, you see that the electric car starts more expensive but after 3 years, the line crosses the gas car line so you know that after 3 years, your return on investment pays off.
How can I have Excel do a vertical line pointing to the date the return on investment pays off?