Final answer:
The ratio problem provided lacks sufficient information to calculate the total monthly income of 'a' and 'b'. We can only establish their income and expense ratios without specific values to determine the absolute monthly incomes.
Step-by-step explanation:
Understanding ratios and budgeting are crucial for managing finances. In this case, the monthly income and expenses of 'a' and 'b' are given in ratios. 'a' and 'b' have an income ratio of 5:4, which means for every 5 parts of income 'a' has, 'b' has 4 parts. Their expense ratio is 4:3, meaning for every 4 parts of expenses 'a' encounters, 'b' spends 3 parts. Despite this, both 'a' and 'b' manage to save Rs. 7,000 monthly. However, the actual question regarding the total monthly income is ambiguous - whether it refers to the combined total income of 'a' and 'b' or the individual incomes of 'a' and 'b' is unclear.
In typical budgeting scenarios, a straightforward arithmetic approach is taken to determine the disposable income or savings. But in this problem, we would need additional data to calculate the actual incomes of 'a' and 'b'. For instance, if the total expenses for each could be determined, Rs. 7,000 could be added back to each to find the respective incomes. Once 'a' and 'b's' individual incomes are known, they can be summed to find the total monthly income.