Oh.
I have to pay 28k * 4
So it makes sense if I do 28k each month with the 10x reward + 5% cb turned on.
This way I can get 2800 points worth 700 ₹ and 500 = 1200 ₹ . Cost to turn on these 2 features will be 700.
In 90 days I can get 1200*3 = 3600.
So after 700 charges I will get 2900 ₹ profit on 28000*3=84000
Hence the benefit will probably be 3.4%.
I hope I am doing the calculation correctly.