Respuesta :

Answer:

D. -9-12=-21

Step-by-step explanation:

Which expression is equivalent to -21?

A. 9-(-12) = 9+12 = 21

B. 9+(-12)  = 9-12 = -3

C. -9+12 = -9+12 = 3

D. -9-12=-21

Answer:a

Step-by-step explanation:because -9 +-12=_21