One way of knowing the correct answers, we substitute the ordered pairs to the function and see whether it would make the function true.
3x – 4y = 21
A. (−3, 3)
3(-3) – 4(3) = 21
-21 = 21 ---------------> not equal
B. (−1, −6)
3(-1) – 4(-6) = 21
21 = 21 ---------------> equal
C. (7, 0)
3(7) – 4(0) = 21
21 = 21 ---------------> equal
D. (11, 3)
3(11) – 4(3) = 21
21 = 21 ---------------> equal
