Answer:
0.5 hour
Step-by-step explanation:
Given
Speed of Dina = 10 km/h
Distance = 20 km
So the time Dina taken to complete the track is:

The time taken by Dina is 2 hours. As masha started with dina but she was 4 km of the path left to cycle,
her distance covered in 2 hours was:

So we know the time and distance:
Now,

We have to calculate the time that will be needed by MAsha to complete the track:
As we know the speed and remaining distance

Masha needs 0.5 hour to complete the track ..
Answer:
D
Step-by-step explanation:
I'm not 100% percent sure but I believe its that one
The handshake is an illustration of combination, and the values of n and r are 21 and 2, respectively
<h3>How to determine the values of n and r?</h3>
The number of students in the class is 21.
This represents the value of n
i.e. n = 21
Each student shakes hand with another student (i.e. 2 students per handshake)
This represents the value of r
i.e. r = 2
Hence, the values of n and r are 21 and 2, respectively
Read more about combination at:
brainly.com/question/11732255
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