7. What are the measures of ∠a, ∠b, and ∠c?

a = 45

b = 105

c = 30 .

Step-by-step explanation:

a +  135 = 180  {Linear pair}

         a = 180 - 135

a = 45

d = 30    {Vertically opposite angles}

WA // YZ

c = d   { Alternative interior anlges}

c = 30

a +  b+ c = 180  {Angle sum property of triangle}

45 + b + 30 = 180

       b + 75 = 180

b = 180 -75

b = 105

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