After trying some other possible economic activities such as gold and sand, finally tobacco was the activity that brought prosperity to Virginia's colonial economy. It was a really successful crop in this area that helped to invest in different activities for the growing economy that needed to purchase some imported products from England as well as the workforce from slavery.
CivilWarSaga.com says, It is estimated that at least 100,000 Union soldiers were boys under 15 years old and about 20 percent of all Civil War soldiers were under 18. Hope this helps :)
This is because the opposite interior angles are congruent and the opposite of the middle of the angle (Y) so W will be in the middle and you dont use Y