Prawn math joke

This question can be set to the volume of a cup, so it can be concluded that: because the orange juice is full at first, orange juice is originally A. If you drink 30%a orange juice and fill it with water, you add 30%a water, drink 25%a and fill it up again, then this time you add 25%a water, drink 45%a and fill it up again. Because I added 100%a water and drank it all, I drank a glass of water and orange juice, so there was as much orange juice as water.

I hope I can help you. It's hard to hit by hand. Do not copy,,,,