Answer:
-2
Step-by-step explanation:
To perform matrix subtraction, it is approached thus ;
Given that :
A = [a1 a2]
___[a3 a4]
B = [b1 b2]
___[b3 b4]
A - B = [a1-b1 a2-b2]
_____ [a3-b3 a4-b4]
Hence, using these concept ;
The missing subtraction corresponds to :
A = 2 and B = 4
A - B = 2 - 4
A - B = - 2