Parallelogram Side Length: Finding X When Adjacent Side is 15

To find the values of $x$ and $y$ for the parallelogram ABCD, we use the property that opposite sides of a parallelogram are equal.

1. Opposite sides AB and DC must be equal, therefore:

$x = 15$

2. Opposite sides AD and BC must also be equal, therefore:

$y = 7$

Thus, the values of the unknowns that make ABCD a parallelogram are $x = 15$ and $y = 7$.

This corresponds to choice 1: $x = 15, y = 7$.