Solution:

Given,
- Average salary of unskilled workers = Rs.10,000
- Average salary of skilled workers = Rs.15,000
- Combined salary = Rs.12,000

Let us assume the number of unskilled workers to be x and the number of skilled workers to be y.

Calculation of Percentage of Skilled Workers:

1. Calculation of Total Salary:

Total salary of unskilled workers = Rs.10,000x
Total salary of skilled workers = Rs.15,000y

Combined salary = Rs.12,000

Total salary = Total salary of unskilled workers + Total salary of skilled workers

i.e. 10,000x + 15,000y = 12,000

2. Calculation of Ratio of Skilled Workers to Unskilled Workers:

Let us assume the ratio of skilled workers to unskilled workers to be k.

Then, y/x = k

y = kx

3. Calculation of Percentage of Skilled Workers:

Percentage of skilled workers = (y/(x+y)) x 100

Substituting the value of y, we get

Percentage of skilled workers = k/(1+k) x 100

4. Substituting the Values:

Substituting the value of y in the equation (10,000x + 15,000y = 12,000), we get

10,000x + 15,000kx = 12,000

Simplifying, we get

x(3k + 2) = 12

x = 12/(3k + 2)

Substituting this value of x in the equation y = kx, we get

y = 12k/(3k + 2)

5. Final Calculation:

Substituting the value of x and y in the equation Percentage of skilled workers = k/(1+k) x 100, we get

Percentage of skilled workers = k/(1+k) x 100

= (y/(x+y)) x 100

= (12k/(3k + 2 + 12k)) x 100

= (12k/(3k + 2 + 12k)) x 100

= (12k/ (3k + 14)) x 100

Now, as we know the combined salary is Rs.12,000

Hence,

10,000x + 15,000y = 12,000

Substituting the value of x and y, we get

10,000 (12/(3k+2)) + 15,000 (12k/(3k+2)) = 12,000

Simplifying, we get

k = 2

Therefore, Percentage of skilled workers = k/(1+k) x 100

= 2/(1+2) x 100

= 66.67%

Hence, the percentage of skilled workers is 66.67%.

40%