Tìm số nguyên x biết: 9 – 25 = ( 7 – x) – (25 + 7)

9 – 25 = (7-x) – (25 + 7)

9 + (-25) = 7 – x – 25 – 7

-16 = 7 – x – 25 – 7

X = 7 – 7 – 25 + 16

x = -25 + 16

x = -9