I'm having a hard time on this problem. plz . will mark brainliest.
find the value of y.
-20
-87
-31
-42

Step-by-step explanation:

We know: opposite angles in a parallelogram have the same measure.

Therefore we have the equation:

           subtract y from both sides

We know: the sum of the angle measures in the triangle is 180°.

Therefore we have the equation:

         subtitute x = 87

             subtract 149 from both sides

step-by-step explanation:

for exempl this   system of equations   y = x - 3

                                                                y = 2x - 5

look   the line : y = x -3     ( red)

                            the line : y = 2x -5 ( bleus)