Income tax computation

Suppose Mr.A And Mr.B are brothers....
Both r carrying there proprietary business..Mr.A is having a reatail shop while Mr. B is carrying business of ticket booking online and getting commission.

Now here the question is Mr. B does not have bank account so all deposit and all his incomes are deposited in Mr. A account...

Mr. A opts for presumptive income but all his deposit shows a total of 1000000 which is inclusive of Mr. B income

And in next financial year Mr. B opens his separate account in bank and all goes normal but these year...MR. A income shows only ...300000


How to compute Mr. A income...for 1st year and for 2 nd year..plzz explain..very big confusion..