Answer:
45
Step-by-step explanation:
x + 3x = 180
Combine like terms : 4x = 180
180/4 = 45
A scale displaying digits...
recall, slope = rise/run, and that a fraction is undefined when the denominator is 0, meaning this slope has a run = 0.
to make it short, when the slope is undefined, is a flag that we simply have a vertical line. Check the picture below.