Since she already has 7 in her account and she ADDS 3 more each day you would multiply 3 by x which represents the number of days and add that to seven because she already had it. This would equal to Y which represents the total in her account
Let the income of first person be 9x let the income of the second person be 7x difference b/w their weekly income=9x-7x=200 =2x=200 x=100 therefore income of first person is 9x=9×100=RS 900 therefore income of second person is 7x=7×100=RS 700