In this case, we can assume that the parabola's focus is located at the right side, in the x-axis, and the directrix at the left side 2 units away from the vertex of parabola meaning the parabola is facing to the right.
equation of parabola facing to the right:
To find a, it is the distance of the focus from the vertex, meaning if you graph it, it is 2 units away.. so:
After finding the equation of the parabola, find the length of the latus rectum, which the formula is:
substitute the value of a
Hope this helps =)