Question

How does 30 S and 50 S subunits make a 70S ribosome?

Answer 1

Answer:

more mg2+ion in the cytoplasm produce riboporin 1&2 which attract the subunits and make 70s ribosome for the translation process

Answer 2

This not a mathematical addition . 30s and 50s represents their sedimentation constant . Each subunit sediment at a rete of 30s and 50s but when they are combined to a big unit it will sediment at a rate of 70s .
I hope you will get this
Sorry it any mistake as this is my first answer !