Math Problem of the Week

You have two timers (the kind where the sand falls) that measure exactly 7 minutes and 4 minutes.

Can you use these to time the 9 minutes you need to cook an egg EXACTLY?

You cannot estimate the time (“well, the sand looks halfway fallen”, and you cannot break the timers.

Here is the link to submit answers https://forms.gle/a9WAb2g1H1srpG8fA