Selling Price = Cost Price + Profit = 50 + (20% of 50) = 50 + 10 = $60

Savings = 20% of $2000 = 0.20 * 2000 = $400.

Leap years from 2000 to 2024 are 2000, 2004, 2008, 2012, 2016, 2020, and 2024. They will celebrate their birthday in 2000, 2004, 2008, 2012, 2016, 2020, and 2024, totaling 5 birthdays.

Total hours required = 64. Hours worked per day = 8. Days required = 64 / 8 = 8 days.

A non-leap year has 365 days, which is 52 weeks and 1 day. Therefore, if the year starts on a Friday, it will end on a Saturday.

A non-leap year has 365 days, which is 52 weeks and 1 day. Therefore, if the year starts on a Wednesday, it will end on a Wednesday.

2023 is not a leap year, so it has 365 days. 365 days = 52 weeks + 1 day. Therefore, January 1, 2024 will be one day after Sunday, which is Monday.

April has 15 days left after April 15. 100 - 15 = 85 days left. May has 31 days, June has 30 days, and July has 24 days. 15 + 31 + 30 + 24 = 100. So, the date will be July 25.

50 days = 7 weeks + 1 day. Therefore, it will be Saturday, which is 1 day after Friday.

From July 4 to July 31 is 27 days. August has 31 days, September has 30 days, October has 31 days, November has 30 days, December has 31 days, and January has 31 days. 27 + 31 + 30 + 31 + 30 + 31 + 20 = 200 days. Thus, it will be January 20, 2024.

March has 31 days, so from March 15 to March 31 is 16 days. April has 30 days, May has 31 days, and June has 30 days. 16 + 30 + 31 + 23 = 100 days. Therefore, the date will be June 24, 2023.

From October 10 to October 31 is 21 days. November has 30 days. 50 - 21 = 29 days left in November. Thus, it will be November 30, 2023.

The maximum number of days in a month is 31. If today is the 15th, there are 31 - 15 = 16 days left.

31 days = 4 weeks + 3 days. Therefore, the day on the 31st will be three days later than the 1st.

Using Zeller's Congruence, July 4, 1776 falls on a Thursday.

2023 has 365 days, which is 52 weeks and 1 day. December 31, 2023 will be one day before January 1, 2024, which is a Sunday, making it Saturday.

2025 is not a leap year, so it has 365 days. From January 1 to December 31 is 364 days, which is 52 weeks + 0 days. Therefore, December 31, 2025 will also be a Wednesday.

2025 is not a leap year, so it has 365 days. 365 days = 52 weeks + 1 day. Therefore, December 31, 2025 will be one day after Wednesday, which is Thursday.

January 1, 2024 is a Monday. February 29, 2024 is 59 days from January 1, which is 8 weeks and 3 days. Therefore, it will be a Thursday.

From January 1 to March 1, there are 59 days (31 days in January + 28 days in February). 59 days = 8 weeks + 3 days. Wednesday + 3 days = Saturday.

2020 is a leap year, so there are 366 days from January 1, 2020 to December 31, 2020.