If 3x – 9y = 21 and 6x + 3y = 21, which of these could be a value of x or y?

x=4,  y=-1

Step-by-step explanation:

Multiply the second equation by 3:

18x+9y=63

Then summarize  both equations 18x+9y+3x-9y=21+63

21x=84 => x=4

use x=4 in any of initial equations ,for instance in first one:

3*4-9*y=21

12-9*y=21

9y=12-21

9y=-9

y=-1

0/5 is 0, 2/0 is undefined, and 0/0 is indeterminate.

step-by-step explanation:

hope my answer has you!

207/8 is the right