Question

Can you add 2 hours and 45 minutes to 3 hours and 57 minutes by using decimal numbers (2.45 + 3.57)? Explain.


Also, suppose you want to add 3 feet and 7 inches to 5 feet 6 inches. Can you use decimal numbers so that you can add 3.7 to 5.6 to get the total length?
Explain.

Answer 1

To add/subtract something, they must be in the same units

e.g 5 apples + 8 oranges = 13 appleoranges?

so 2 hrs, 45 minutes
= 2 + 45/60 = 2.75 hrs
3hrs, 57 minutes
= 3 + 57/60 = 3.95 hrs

now you can add them:
2.75+3.95 = 6.7 hrs
= 6 hrs + (7/10)(60) minutes
= 6 hrs, 42 minutes

or

2hr + 3hrs = 5 hrs
45 min + 57 min = 102 minute
= 1 hour + 42 minutes
etc

Same method and explanation for #2

Answer 2

1:42