Explanation:

Let’s break down the problem:

- Alloy X has Cu : Al = 6 : 5. In 11 parts, 6 are Cu, 5 are Al.

- Alloy Y has Cu : Al = 5 : 9. In 14 parts, 5 are Cu, 9 are Al.

- Equal quantities are mixed. So, assume 11g of X and 14g of Y (the LCM of 11 and 14 is 154).

Copper:

- In 11g of X: 6g Cu,

- In 14g of Y: 5g Cu,

Total Cu = 6 + 5 = 11g

Aluminium:

- In 11g of X: 5g Al,

- In 14g of Y: 9g Al,

Total Al = 5 + 9 = 14g

However, we should scale both to 154g for equal proportions:

- 154g X: Cu = (6/11)*154 = 84, Al = (5/11)*154 = 70

- 154g Y: Cu = (5/14)*154 = 55, Al = (9/14)*154 = 99

- Total Cu = 84 + 55 = 139

- Total Al = 70 + 99 = 169

- Ratio = 139 : 169

So, the correct answer is:

Option 4, 139 : 169