Equation of line p is y=x+7. Equation of a is y=-x+11. Prove that the lines are perpendicular

The Answer is provided in the explanation!

Step-by-step explanation:

The lines are perpendicular because in both of the equations, the x variables are inverses. Meaning, that y=x+7, the x is positive, and y=-x+11, the x is negative. This shows that the slopes of both equations are 1, meaning the graph will have an X shape, provide that lines are perpendicular because they have an inverse of the same slope!

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180