Suppose a crime was committed. The victim, Abel, says he did not bleed, but that the perpetrator did. We also know that the perpetrator was someone in this class. The blood at the crime scene is type O. How many people in this class could be the perpetrator?

The number of students that there blood type is type O

Explanation:

With simple analogy, Abel is a member of a class, and Abel was not hurt , he is a victim.

The perpetrator is a member of a class (fact 1) and the blood type found on the crime scene is type O(fact 2). To draw conclusion,

The perpetrator is possibly someone from the class with a type O blood type. So a narrow research should be carried out on the blood type of the students in a class and to be more precise , someone who just got hurt , a clear injury and has a blood type of type O would be the possible perpetrator.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.