[tex]I_1,I_2[/tex] Incomes of person 1 and 2
[tex]E_1,E_2[/tex] Expenditure of persons 1 and 2.
You are given the following ratios:
This is 3 equations in 4 unknowns, so we can choose one of the values. I will set
You should be able to solve that system of simultaneous equations to get
The ratio you want is
Its interesting to note that the savings amount comes out as negative for both people...but thats another story.
If you are interested in why i can set without breaking the answer, its because we are only interested in ratios, not the actual levels of income. I am effectively redefining the currency unit of the problem so that has 1 unit.