Explanation:

- Last year, 5 companies had an average of 16 non-working days each. This totals to 5 x 16 = 80 non-working days.

- This year, 3 companies increased their non-working days by 10 each, resulting in an increase of 3 x 10 = 30 days.

- The remaining 2 companies decreased their non-working days by 5 each, resulting in a decrease of 2 x 5 = 10 days.

- Total non-working days this year = 80 + 30 - 10 = 100 days.

- The average number of non-working days for the 5 companies this year = 100 / 5 = 20.

The correct option is:

Option 3: 20

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