Ill give you the basic idea of how to proceed with these but make sure to do them and practice them because they can become challenging.
#1. We can look at the two sides that are across from each other and because they are located where they are, they are equivalent.
So we now know that 2x = y - x.
This allows us to solve for x and y
#2 In this problem the two values are on a striaght line so they must equal 180 degrees in total and they must be opposite values.
#3 3x+6 = y
With this information, you should be able to get the concept down. Write me if you have anymore questions
