Explanation

Initially, the salaries are in the ratio 1:3:4. Let's assume the salaries are x, 3x, and 4x.

After the increases:

A's salary increases by 5%, so the new salary is x + 5% of x = x + 0.05x = 1.05x

B's salary increases by 10%, so the new salary is 3x + 10% of 3x = 3x + 0.10(3x) = 3.30x

C's salary increases by 15%, so the new salary is 4x + 15% of 4x = 4x + 0.15(4x) = 4.60x

Now, let's find the ratio of the increased salaries:

1.05x : 3.30x : 4.60x

To simplify, divide each term by 0.05x (the smallest common multiple):

1.05x / 0.05x = 21

3.30x / 0.05x = 66

4.60x / 0.05x = 92

So, the increased salaries are in the ratio 21:66:92.