The widths of the flex items are computed based on the ratios of the flex-grow value

Hi everyone,
Iam not understanding this part of flex “The widths of the flex items are computed based on the ratios of the flex-grow value.” could anyone help?

I always refer to this page for flex properties:

They have a nice graphical demonstration of flex-grow.

Hi, Thanks for help.
I went there it says flex two means 2times width of 1st item. what if i want to distribute space between two children in 30% and 70%?

Scroll down a little more on that page until you reach flex-basis.