Both 2 and 3 have the general form a = mx + b, which I think is the very first lesson from my geometry class?  The &quot;Common Core&quot; standard has slopes of lines in grade 6, but their standard doc entitled &quot;Ratios and Proportional Relationships&quot; doesn&#x27;t even contain the word &quot;intercept&quot; which I assume is an indicator of the whole country going to Hell in a handbasket.