M∠CBT is not 120°.
You have to notice the start of the measure of the angle is on the point of C. It is the 0°.
If the segment BT is straight up from the point of B, its angle will be 90°.
Since the segment does not form a right angle, its measure of angle is less than 90° but more than 0°
Answer:
In the mid-19th century, the quest for control of the West led to the annexation of Texas and the Mexican–American War. ... This expansion led to debates about the fate of slavery in the West, increasing tensions between the North and South that ultimately led to the collapse of American democracy and a brutal civil war.
Step-by-step explanation:
The result follows directly from properties of modular arithmetic:
That is,
means we can write 
for some integer 
. Then
and taken mod 12, the first term goes away, so
etc
