Answer: 
Step-by-step explanation:
1. By definition, the associative property of addition is:

This property says that you can group the numbers in different ways and you will obtain the same result.
2. Therefore, if you have the following expression:

You apply the Asociative property of addition by regrouping the numbers as following:

3. Then, you can conclude that the correct option is B.
Answer:
42 13/20 km
Step-by-step explanation:
10 3/10+9 7/20+14 7/10+ 8 9/20=41+ (6+7+14+9)/20=41 + 1 13/20= 42 13/20 km
9514 1404 393
Explanation:
Make use of the properties of equality.
a = 2b +6 . . . . . given
a = 9b -8 . . . . . given
2b +6 = 9b -8 . . . . . . . substitution property of equality
6 = 7b -8 . . . . . . . . . . . subtraction property of equality
14 = 7b . . . . . . . . . . . . . addition property of equality
2 = b . . . . . . . . . . . . . . . division property of equality
b = 2 . . . . . . . . . . . . . . symmetric property of equality