The sum of two numbers, x and y, is 12. the difference of x and two times y is 6. what are the values of x and y? x = 8, y = 4 x = 10, y = 2 x = 18, y = -6 x = 20, y = -8

The answer is the second choice.
x = 10, y = 2

The sum of two numbers x and y is 12.
x + y = 12

The difference of x and two times y is 6.
x - 2y = 6

From there I subtracted the bottom equation from the top equation, so it would look like:
(x + y) - (x - 2y) = (12) - (6)
x + y - x + 2y = 6
3y = 6
y = 2

from there you could plug in y as 2 in any equation above. I will use the top equation here.
x + y = 12
x + (2) = 12
x = 10

That is the answer to your question