Answer:
[tex]y=10[/tex]
Step-by-step explanation:
We know that the sum of these two angles is 180 degrees. Why? Imagine if the horizontal line was perfectly horizontal. There would be two 90 degree angles, one at each intersection of the vertical lines. If the rotate the line, we haven't magically removed or added degrees, so we know it is still 180 degrees.
Hence, the equation is:
[tex]180=120+6y\\60=6y\\\bold{y=10}[/tex]
