In the diagram, if l1 || l2, what is the value of y?

To find the value of $y$, we use the properties of parallel lines intersected by a transversal.
From the diagram, $l_1 \parallel l_2$, and $l_3$ is a transversal.

Step 1: Identify the relationship between $x^\circ$ and $3x^\circ$.
The angle marked $x^\circ$ is an interior angle on the left side of the transversal $l_3$, between $l_1$ and $l_3$.
The angle marked $3x^\circ$ is an interior angle on the right side of the transversal $l_3$, between $l_2$ and $l_3$.
These two angles are alternate interior angles. Since $l_1 \parallel l_2$,