Answer:

Step-by-step explanation:
Since there are 20 students, this will be the denominator.
Now, to find how many students have a dog and a cat, you need to subtract all the numbers with 20. The leftover number will be the amount of students.
7+8+8=23
23-20=3
So, there are 3 students who have a dog and a cat.
So, the fraction will be 
Eaqu de la suósi porque etas luncio
Answer:
My sister will swing the total distance = 40 feet
Step-by-step explanation:
On the first swing my sister travels a distance of 8 feet.
In every successive swing she travels 80% of the distance of the previous distance.
So the sequence formed by the distance traveled in every swing will be a geometric sequence.
First term of the sequence 'a' = 8 feet
common ratio 'r' = 0.80
Since this sequence is an infinite geometric sequence,
Sum of this sequence =
[Since r < 1]
= 
=
= 40 feet
Therefore, my sister will cover the total distance = 40 feet