Last year, the ratio between the salaries of A and B was 3 : 4. But the ratios of their individual salaries between last year and this year were 4 : 5 and 2 : 3 respectively. If the sum of their present salaries is Rs. 4160, then how much is the salary of A now ?

Explanation:-

let the salaries of A and B last year be Rs. 3x and Rs. 4x respectively.
Then, $$\eqalign{ & {\text{A's present salary}} \cr & = {\text{Rs}}.\left( {\frac{5}{4} \times 3x} \right) \cr & = {\text{Rs}}{\text{.}}\left( {\frac{{15x}}{4}} \right). \cr & {\text{B's present salary}} \cr & = {\text{Rs}}{\text{.}}\left( {\frac{3}{2} \times 4x} \right) \cr & = {\text{Rs}}.6x. \cr & \therefore \frac{{15x}}{4} + 6x = 4160 \cr & \Rightarrow 39x = 4160 \times 4 \cr & \Rightarrow x = \frac{{4160 \times 4}}{{39}}. \cr & {\text{So,}} \cr & {\text{A's present salary}} \cr & = {\text{Rs}}{\text{.}}\left( {\frac{{15}}{4} \times \frac{{4160 \times 4}}{{39}}} \right) \cr & = {\text{Rs}}.1600. \cr}$$