Answer:
Islamic mathematicians quickly adopted the Indian system of numerals, which we know today as Arabic numerals. Other contributions included creating algebra, the use of decimals, mathematical induction, and trigonometry, among others.
Answer:
By dividing into state and national levels.
1. Germany kept on attacking passing merchant ships and passenger ships with submarines.
2. Germany wanted to be in an alliance with Mexico, which made the U.S. worry they were going to be attacked.
When writing an essay like this, I would devote one paragraph to talking about how supply and demand dictate prices, and another paragraph to how international trade fuels economic growth.