Let's begin by listing out the information given to us:
There are four students: n = 4
Number of students to be selected: r = 2
To calculate the combination of 2 students to be chosen, we use:

Therefore, there 12 possible combinations from these
20 animals - 2 rabbits = 18 animals
18 animals + 2 gerbils = 20 animals.
20 animals / 4 = 5 animals
There are 5 rabbits and 15 gerbils now.
At the start 2 rabbits were sold so add that on.
5 + 2 = 7
There were 7 rabbits.
There weren't any twin gerbils then.
15 - 2 = 13.
There were 13 gerbils and 7 rabbits to start with.
Hope This Helps You!
Good Luck Studying :)
Answer:
120
Step-by-step explanation:
4*30=120
I think it’s pretty interpretative, the reason I didn’t divide 483/2 like you would normally with a triangle, is because there are 2 triangles in a trapezoid. Also you can split the two triangles off the trapezoid because in a trapezoid the train for will awkward be right.