1 day 10 hours + 3 days 15 hours = ?

SOLUTION:
\(\begin{aligned} 1\,\text{day}\;10\,\text{hours}\\ \underline{+\;3\,\text{days}\;15\,\text{hours}}\\ 4\,\text{days}\;25\,\text{hours} \\\hline\end{aligned}\)

1 DAY = 24 HOURS

4 days 25 hours = 5 days 1 hour OR
4 days 25 hours = (4 x 24) + 25 hours = 121 hours

3 weeks 2 days + 1 week 6 days = ?

SOLUTION:
\(\begin{aligned} 3\,\text{weeks}\;2\,\text{days}\\ \underline{+\;1\,\text{week}\;6\,\text{days}}\\ 4\,\text{weeks}\;8\,\text{days}\\\hline \end{aligned}\)

1 WEEK = 7 DAYS

4 weeks 8 days = 5 weeks 1 day OR
4 weeks 8 days = (4 x 7) + 8 days = 36 days

4 years 9 months + 3 years 8 months + 10 years 4 months = ?

SOLUTION:
\(\begin{aligned} 4\,\text{years}\;\;\;9\,\text{months}\\ 3\,\text{years}\;\;\;8\,\text{months}\\ \underline{+\;10\,\text{years}\;\;\;4\,\text{months}}\\ 17\,\text{years}\;21\,\text{months}\\\hline \end{aligned}\)  

1 YEAR = 12 MONTHS

17 years 21 months = 18 years 9 months OR
17 years 21 months = (17 x 12) + 21 months = 225 months

5 days 5 hours - 2 days 9 hours = ?

SOLUTION:
5 hours cannot be subtracted from 9 hours. So, we convert 1 day to 24 hours to be subtracted with 9 hours.

1 DAY = 24 HOURS
5 days 5 hours = 4 days 29 hours

\(\begin{aligned} 4\,\text{days}\;29\,\text{hours}\\ \underline{-\;2\,\text{days}\;\;\;9\,\text{hours}}\\ 2\,\text{days}\;20\,\text{hours}\\\hline \end{aligned}\)

19 weeks - 3 weeks 4 days = ?

SOLUTION:
0 day cannot be subtracted with 4 days. So, we convert 1 week to 7 days to be subtracted with 4 days.

1 WEEK = 7 DAYS
19 weeks = 18 weeks 7 days

\(\begin{aligned} 18\,\text{weeks}\;7\,\text{days}\\ \underline{-\;3\,\text{weeks}\;4\,\text{days}}\\ 15\,\text{weeks}\;3\,\text{days} \\\hline\end{aligned}\)

4 years 3 months - 10 months = ?

SOLUTION:
3 months cannot be subtracted from 10 months. So, we convert 1 year to 12 months to be subtracted with 10 months.

1 YEAR = 12 MONTHS
4 years 3 months = 3 years 15 months

\(\begin{aligned} 3\,\text{years}\;15\,\text{months}\\ \underline{-\quad\quad\quad10\,\text{months}}\\ 3\,\text{years}\;\;\;5\,\text{months} \\\hline\end{aligned}\)

5 x 4 days 10 hours = ?

SOLUTION:

\(\begin{aligned} 4\,\text{days}\;10\,\text{hours}\\ \underline{\times\quad\quad\quad\quad\quad5}\\ 20\,\text{days}\;50\,\text{hours} \\\hline\end{aligned}\)

1 DAY = 24 HOURS
20 days 50 hours = 22 days 2 hours

3 x 2 weeks 4 days = ?

SOLUTION:

 \(\begin{aligned} 2\,\text{weeks}\;4\,\text{days}\\ \underline{\times\quad\quad\quad\quad\quad3}\\ 6\,\text{weeks}\;12\,\text{days}\\\hline \end{aligned}\)

1 WEEK = 7 DAYS
6 weeks 12 days = 7 weeks 4 days

4 x 10 years 7 months = ?

SOLUTION:

 \(\begin{aligned} 10\,\text{years}\;7\,\text{months}\\ \underline{\times\quad\quad\quad\quad\quad\quad\quad4}\\ 40\,\text{years}\;28\,\text{months}\\\hline \end{aligned}\)

1 YEAR = 12 MONTHS
40 years 28 months = 42 years 4 months