The diagram below show the situation given in the problem:
We know that the diagonals of a parallelogram bisect each other, which means that AE=CE and BE=DE; using the second equality we have that:
[tex]\begin{gathered} y+10=4y-8 \\ 4y-y=10+8 \\ 3y=18 \\ y=\frac{18}{3} \\ y=6 \end{gathered}[/tex]
Therefore, the value of y is 6 and the answer is A.
