Angle y and angle x form vertical angles. angle y forms a straight line with the 80 degree angle and the 60 degree angle. write and solve an equation to determine the measure of angle x

If angle y and angle x form vertical angles, then they ARE vertical angles.  Vertical angles have the SAME degree measure.  If angle y forms a straight line with the 80 degree angle and the 60 degree angle, this means that adding angle y, the 80 degree angle, and the 60 degree angle gives you a straight line.  A line is 180 degrees.  So, angle y's measure=180-(80+60).  Since measure of angle x equals measure of angle y, the equation is m<x=180-(80+60).

Let's solve.  m<x=180-(80+60).  m<x=180-140.  m<x=40 degrees.

m<x=180-(80+60); m<x=40 (degrees)