Explanation:
If both sides are the same identical expression, then we have two lines that occupy the same space so to speak. One line is perfectly on top of the other line. This produces the infinitely many intersection points to lead to infinitely many solutions.
In order to have ax+b turn into 12x+24, the only way we can do that is with a = 12 and b = 24.
Then 12x+24 = 12x+24 has infinitely many solutions.
