Narayan spends 30% of his income on education and 50% of remaining on food. He gives Rs. 1000 as monthly rent and now has Rs. 1800 left with him. What is his monthly income?

Narayan's saving and rent = 1000 + 1800 = Rs. 2800
Let his monthly income be Rs. 100
30% of his income he spent on education i.e. Rs. 30
Remaining = 100 - 30 = 70
50% of remaining on food = $$\frac{{70 \times 50}}{{100}} = {\text{Rs}}{\text{. 35}}$$
Now, that 35 must be equal to his saving and rent i.e.
35 = 2800 then,
1 = $$\frac{{2800}}{{35}}$$
100 = $$\frac{{2800 \times 100}}{{35}} = {\text{Rs}}{\text{. 8000}}$$
So, his income = Rs. 8000