
Answer:
D) 4
Step-by-step explanation:
β9 + 12 + (unknown) + β8 = β1
Start by going through and testing each option
β9 + 12 + 2 + β8 =
3 + 2 + β8 =
5 + β8 =
β3
β3 β β1
A) 2 is not possible.
β9 + 12 + β2 + β8 =
3 + β2 + β8 =
1 + β8 =
β7
β7 β β1
B) β2 is not possible.
β9 + 12 + β4 + β8 =
3 + β4 + β8 =
β1 + β8 =
β9
β9 β β1
C) β4 is not possible.
From this, D is looking like the answer. But to be sure, test it.
β9 + 12 + 4 + β8 =
3 + 4 + β8 =
7 + β8 =
β1
β1 = β1
D) 4 is the answer.