How was the south to become part of the union again? ?

They went to war with the North, it was called the American Civil War :) hope this helps! And also, South is capitalized ;)

a. because the u.s. was the leading with the most technology, economy, etc. also was teamed with other allies witch boosted the economy and materials to improve technology and use it.

the installment plan of the 1920s, an arrangement that allowed people to buy what they wanted with a small down payment and pay off the rest in monthly installments, provided americans a way to own what they did not have the money to buy.