If 15 January 2019 was a Tuesday, then what day of the week was it on 29 January 2020?

The correct option is Wednesday.

To find the day of the week on 29 January 2020 given that 15 January 2019 was a Tuesday, we can calculate the total number of odd days between these two dates.

Step 1: Calculate odd days from 15 January 2019 to 15 January 2020

The period from 15 January 2019 to 15 January 2020 covers 1 complete ordinary year (365 days), as February 2019 has 28 days.

Number of odd days in 365 days = $\frac{365}{7}$ = 52 weeks and 1 remainder day.

So, 15 January 2020 is 1 day ahead of Tuesday, which is Wednesday.

Step 2: Calculate remaining days from 15 January 2020 to 29 January 2020

Number of days between 15 January 2020 and 29 January 2020 = 29 - 15 = 14 days.

Number of odd days in 14 days = $\frac{14}{7}$ = 2 weeks and 0 remainder days.

Step 3: Determine the final day

Total odd days from 15 January 2019 to 29 January 2020 = 1 + 0 = 1 odd day.

Adding 1 day to Tuesday gives Wednesday.

Therefore, 29 January 2020 was a Wednesday.