See attached picture for steps and answer:
I think they should keep it around, even if it might not be the most efficient strategy. After all, what if you need to solve a problem using multiple strategies?
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 
Answer:
a. 1/2
b. 5/3
c. 0
d. undefined
Step-by-step explanation: