I am new with Apple products. i just bought iMac 27 5k, 3.3GHz quad-core Intel Core i5 , 8GB Ram, 2TB Fusion Drive. i wanted to know if it is possible to increase its RAM? i asked the dealer here in Pakistan but they say you can't upgrade the RAM. you will see to send the to Apple USA which will be another expensive story.

I want to know if i can increase its RAM to 32GB or 64GB?

Also what are the good supported ram which was not really expensive but affordable. can you guys directly what kind of ram i need and how to upgrade the ram? i have no idea what of ram i need to purchase online, its so confusing