The ratio of the incomes of A and B last year was 4 : 3, respectively. The ratios of their individual incomes of the last year and the present year are 3 : 4 and 5 : 6, respectively. If their total income for the present year is ₹8.04 lakh, then the income of B last year was:

Let the last year and present income of the A be 3x and 4x respectively.
Let the last year and present income of the B be 5y and 6y respectively.
The ratio of the last year incomes of A and B = 4 : 3
3x : 5y = 4 : 3
$$\frac{3x}{5y} = \frac{4}{3}$$
x = $$\frac{20y}{9}$$
Total income for the present year =  ₹8.04 lakh
4x + 6y = ₹8.04 lakh
$$4 \times \frac{20y}{9} + 6y = 8.04$$
$$ \frac{136y}{9} = 8.04$$
y = 72.36/136 = 18.09/34
Last year income of B = 5y = 5 $$\times \frac{18.09}{34}$$ = 2.66 ~ ₹2.7 lakh