I think 24 but im not 100 percent sure more like 60 .
X = 3 is the answer for your question
Assuming T, B and N are all on the same line, then we can say
BT + TN = BN
which is the segment addition postulate.
Subtract TN from both sides to get
BT + TN = BN
BT + TN - TN = BN - TN
BT = BN - TN
BN - TN = BT
Which is what choice C is saying. Therefore the answer is choice C.