Which of the following made it possible for scientists to practice direct observation

You said "Which of the following" so do you mind providing the answer choices. ;)

for this case we have the following equation:

we apply distributive property to the terms within parentheses.

subtracting 2 on both sides of the equation:

you will need these

an outline of all three paragraphsan identification of the historical era that you are writing aboutan explanation of the term mass productiona description of two ways new technology affected industrya conclusion that shows how new technologies allowed industrialization to grow