Hint: Use the basic concept of Indian number system and break the numbers to place commas easily.
Complete step by step answer:
As we know when we write numbers in the form of numerals then we start from last and place comma after 3 digits then after that we will continue placing comma after 2 subsequent digits going towards right to left.
So, in numerals it can be written as,
$\Rightarrow 73,00,000 + 75,000 + 307 = 73,75,307 $
So, required answer will be $73,75,307$
NOTE: - Whenever you come up with this type of problem, always break it into different parts like we did above and then add all. This will reduce the chance of error.