which equation is true?
A) (12 + 17) - 9 = (23 -7) + 4
B) 12+ (17 -9) = 23 - (7 + 4)
C) ( 12+ 17) - 9 = 23 - ( 7+4)
D) 2+ (17 - 9) = 23 - (7+4)