R have 200 divided by 20 equals 10 records. And each record means a row of an entity therefore to do join for each block of R with S 1 block access for R and by keeping that block their 20 multiplied by 30 block access for S.
Similarly, for all blocks of R.
Therefore, total 10(for Each BLOCK OF R) PLUS 20 MULTIPLY 30(FOR THEIR JOIN) EQUALS 6010.