Radials radiate outwards from a station, just like the magnetic bearings on a compass rose. So, the outward radial is just the reciprocal of the inbound bearing.
The key is the “TO” flag. If you were to be flying a heading of 210 degrees you would fly TO the navaid.
Draw it out on a piece of paper, or refer to a chart or your study material. Orientation questions like this benefit most from visuals.
Also, don't get confused thinking this instrument is a gyroscopic compass card. It is not slaved to any inputs, the course showing on the face is manually dialed in and remains as set until you change it.
“Crossing a radial” simply means that you are not tracking along it either inbound or outbound to/from the navaid. (You are going across it at some angle.) This is a useful technique for identifying intersections if you have two VOR receivers: With one dialed in to the radial you are tracking, set the other one to the other VOR station that defines the fix, and dial in that radial on your OBS. When the CDI bar centers up it means you are crossing that radial.