Answer:
[tex]x=4,\\y=8[/tex]
Step-by-step explanation:
Notice that in the diagram, opposite sides are equal. This is true for any rectangle, so even without the equal sides being marked, we'd know that each pair of opposite sides have the same length.
Therefore, we can set up the following equations and solve for [tex]x[/tex] and [tex]y[/tex]:
[tex]2y=y+8,\\y=\boxed{8}[/tex]
[tex]4x-8=2x,\\-8=-2x,\\x=\boxed{4}[/tex]
