An independent variable is a variable that can stand by itself. It can be predefined or ultimately just stand alone.
Try common ratio, because b represents a constant variable. (I’m not 100% but it may be this)
I would say that the sectional tensions strengthened during the 1850s mostly because of slavery. As you already know, historically, the North and the South of US were very different. The North went out of its way to abolish slavery, whereas the South was pro-slavery. This is what created many tensions, and later on, even more wars between these two sections.
While the Pope had granted Spain sovereignty over the New World, de Las Casas argued that the property rights and rights to their own labor still belonged to the native peoples. Natives were subjects of the Spanish crown, and to treat them as less than human violated the laws of God, nature, and Spain.
