Given a parallelogram, solve for x.

In parallelogram SALE, opposite sides are equal. Thus, $SA = EL$ and $SE = AL$. We are given $SA=3$ and $EL=3$, which is consistent. We set $SE = AL$, so $3x+4 = 5x-6$. Solving for x, we get $2x = 10$, so $x=5$.