Solution :
Let, income and saving of Adam is 9x and 3y.
Similarly income and saving of Rosy is 7x and y.
We know,
Income = Saving + Expense
Now, it is given that their expense is same and it is ₹12000 per month.
For Adam, 9x = 3y + 12000 ...1)
3x = y + 4000
For Rosy, 7x = y + 12000
21x = 3y + 36000 ...2)
Subtracting 1) from equation 2), we get :
12x = 24000
x = ₹2000
Therefore, monthly incomes of Adam and Rosy is ₹18000 and ₹14000 respectively.