Question

What is the value of y

Answer 1

sum of interior angles in a triangle = 180
so
y + y - 12 + 56 = 180
2y + 44 = 180
2y = 136
y = 68

Answer
C. 68°

Answer 2

if you isolate y from the equation y+(y-12)+56=180 (adding all the angles together to make 180), you would get 68 degrees