I have answers that I guessed. not sure how to work it out properly. The possible answers were 4, 9, -10, -20, -6. The correct answer was 4 and -6 but i dont know why!​

I have answers that I guessed not sure how to work it out properly The possible answers were 4 9 10 20 6 The correct answer was 4 and 6 but i dont know why class=