The use of gunpowder. Specifically military use, this helped fight wars and win wars because they were able to use the gunpowder. (Not 100% sure)
One important invention that was created in the Song dynasty was the invention of paper money.
Before paper money, people in China used metal and stone coins, which were bulky and could get really heavy at times. However, the paper money made it much easier to carry currency over long distances for trading without the large weight that metal coins had.
This invention affects the whole world today, as many countries have adopted the concept of paper money and still use it. Let me know if you need any clarifications or extra info, thanks!
the sale price is (1.00 - 0.77)($87), or 0.23($87), or $20.01.
f(x)=2/3x-8, which give g(x) the greatest value.