Answer:
Explanation:
Quadrilateral ABCD is a parallelogram.
opposite angles of a parallelogram are equal in measure.
Opposite sides of a parallelogram are equal.
3y - 1 = y + 15
3y - y = 15 + 1
2y = 16
y = 16/2
y = 8
AD = 3y - 1 = 3*8 - 1 = 24 - 1
AD = 23