The question in letter f is:
Find the locus of points whose:
f) distance from the y axis is 7.
To do that we need to remember the cartesian plane,
The black axis is the Y axis, and the blue axis is the X axis. Do you understand??
After that, we need to find all points that has a distance of 7 units from the Y axis... I'm gonna draw in red color.
Finally, all points in the red line has the distace of 7 units from the Y axis.