A year ago their salaries was 3:4

let their salaries be 3p and 4p respectively

Ratio b/w the individual salary of last year and this year;

for A = 4/5

current salary be x;

so 3p/x=4/5

x=15p/4

for B = 2:3

4p/y=2/3

y=6p

Now;

x+y=8580

putting the value of x and y we get

p=880

x=15p/4

then, x=3300

Ans(b)3300

let their salaries be 3p and 4p respectively

Ratio b/w the individual salary of last year and this year;

for A = 4/5

current salary be x;

so 3p/x=4/5

x=15p/4

for B = 2:3

4p/y=2/3

y=6p

Now;

x+y=8580

putting the value of x and y we get

p=880

x=15p/4

then, x=3300

Ans(b)3300