Brokerage on order executed in multiple prices

Suppose I place order to buy 5 lots of GBPINR @104CE. But only 1 lot got executed. I modified the price and then remaining 4 gets executed. Will I hav to pay brokerage of Rs20 or Rs40 ( ie for 1 transaction or transaction?

Separate brokerage for each order. In your case two brokerage will be applicable.

@NitiSinha @China_virus
Only Rs.20 will be deducted because it still is only one order. Saying this because I have done this in past and only Rs.20 brokerage was charged.
@ShubhS9 can you confirm this ?

You will pay brokerage of Rs.20 as only a single order is executed. Refer to these threads -

Right. The order remains the same, so brokerage will be Rs. 20 only.