Can I use two different size RAM?

Hi All,

Quick question. So I have a 2019 27inch iMAC which at the time of purchase to keep cost down I took the default 8GB ram option (i.e. it has 2x 4GB). I would like to now upgrade this and have purchased 2 x 16GB (of the correct specification).

My question is can I just add the two new 2 x16GB RAMs and therefore have 40GB RAM in total or is it not wise/possible to have 2 mixed sizes and I should remove the 2 x 4GB and just go with the 2 x 16GB?

Thanks