My lo is 3 months and on mixed feed, currently about 80% breastmilk and 20% formula. She is only pooing once every 4-7days, should i be concern?

yes it's perfectly normal! Most breastfed babies can go up to a week without any motion diapers. As breastmilk is highly digestible. So don't worry about it!

Yes it's normal mummy. Don't be worried about it. You can also do some tummy massage to improve the digestive system of your infant.

Don't worry. It's normal. As long as baby poos and not more than a week I wouldn't worry.