When joining only two clauses separated with the conjunction AND, a comma is OPTIONAL. It can be omitted when there isn't a new subject.
However, using a comma in such sentences is ALWAYS correct so it is better to use one, if you are not sure, whether you should include it.

Hi Vikram

Can you please tell me which version of MGMAT you are using and which page has this below quoted info.

As far as MGMAT is concerned, it says in the punctuation section that "DO NOT USE A COMMA BEFORE AND TO SEPERATE TWO VERBS THAT HAVE THE SAME SUBJECT"

However, in the case you are mentioning,I too think that there should be a comma and a conjunction to join two clauses. Can you tell the page number of MGMAT book where it says the same.

vikram4689 wrote:MGMAT SC says "if you join 2 clauses with and, you can put an optional comma before the and."
I think "comma" is imperative. Can anyone give an instance where it is optional[/img]

Kasia@MasterGMAT wrote:When joining only two clauses separated with the conjunction AND, a comma is OPTIONAL. It can be omitted when there isn't a new subject.
However, using a comma in such sentences is ALWAYS correct so it is better to use one, if you are not sure, whether you should include it.

@Kasia: OG-12 Q.137 uses the comma while joining 2 relative clauses. Both of these are NOT independent clauses then why ",BUT" is used to separate them

@shekhar: It is in PARALLELISM chapter in 4th ed.

vikram4689 wrote: OG-12 Q.137 uses the comma while joining 2 relative clauses. Both of these are NOT independent clauses then why ",BUT" is used to separate them

When we are joining two clause we have to use a comma. The two clause can be dependent or independent. In OG-12 #137, the since both are clause they are joined by a comma.

Refer this : https://www.beatthegmat.com/usage-of-and ... tml#479906

relative clauses are adjectives, modifying nouns, hence don't need a comma. We need a comma when we want it as a non-essential modifier.

The child who was playing on the field is my brother. - here "who was playing on the field" is a relative clause so we don't need a comma.

Hope this helps !!

Kasia@MasterGMAT wrote:When joining only two clauses separated with the conjunction AND, a comma is OPTIONAL. It can be omitted when there isn't a new subject.
However, using a comma in such sentences is ALWAYS correct so it is better to use one, if you are not sure, whether you should include it.

Kasia can you pls provide one example of It can be omitted when there isn't a new subject.