[IMAGE_PLACEHOLDER]

In the figure, $PQRS$ is a trapezium with $PQ$ parallel to $SR$.

The diagonals of the trapezium meet at $X$.

$U$ lies on $SP$ and $T$ lies on $RQ$ such that $UT$ is a line segment through $X$ parallel to $PQ$.

The length of $PQ$ is 12 cm and the length of $SR$ is 3 cm.

What, in centimetres, is the length of $UT$?