Reference frame S’ passes reference frame S with a certain velocity as in figure 37-9. Events 1 and 2 are to have a certain spatial separation %u0394x’ according to the S’ observer. However, their temporal separation %u0394t’ according to that observer has not been set yet. Figure 37-30 gives their spatial separation %u0394x according to the S observer as a function of %u0394t’ for a range of %u0394t’ values (0 to 9ns). The vertical axis scale is set by %u0394x(sub a)=10.m. What is %u0394x’?