C because i learned it from xxxx xxx
Center:
Center is a point in space, which is at equal distance from all the others points in that space.
Answer:

Step-by-step explanation:
(a+b)(a-b)
-ab+ab-

Answer:
105
Step-by-step explanation:
500 goes into 100, 5 times
21 times 5 is 105
So 21/100 is equal to 105/500
Or you can do
500*0.21=105